Introduction

Pirkei D'Rabbi Eliezer (ch. 50) tells us the Midrash regarding Harvona's deed and reveals that it was not Harvona who stood there, but Eliyahu HaNavi:  

"At that time, what did Eliyahu of blessed memory do? He appeared as Harvona, one of the king's chamberlains, and said: there is a wood (pillar) in the house of Haman from Beit Kodesh HaKodeshim fifty cubits in height, as it says (Kings 1, ch. 7 verse 6): And he made the hall of pillars fifty cubits in length." Immediately the king commanded to hang him on it as it says: "And the king said: hang him on it." And this was the realization of the words: (Ezra 6:11) "a wood (beam) will be torn from his house (and will be made into a gallows from which he will be hanged)" and it says "and they hanged Haman from the wood which he prepared for Mordechai." 

The Midrash introduces two main points:

1) Eliyahu HaNavi appears as Harvona in order to save Am Israel, and

2) The wood (beam) in Haman's house was from Kodesh HaKodeshim, and Haman was punished for this.

We can say that there is a connection between these two points, as we will explain further.

Beit HaMikdash

In spite of the fact that in the simple meaning of the Megillah there is no mention of Beit HaMikdash, Chazal connect the subject of Beit HaMikdash to the Megillah in several places.

The first placed is found in the Gemara, Megillah 11:

" 'In those days as the king sat' – and it is written afterwards 'in the third year of his reign' – Rabbah said: 'as (he) sat (k'shevet)' means 'after his mind was settled (le'achar sh'nityashvah da'ato)'… as is written (Yirmiyahu 29:10): 'since (the exile of) Babylonia completed seventy years'…since he (Achashverosh) saw that seventy years passed and they weren't redeemed, he said: now they will never be redeemed. So he took out the vessels of the Temple and used them."

Achashverosh specifically chooses to use the vessels of the Mikdash, the spiritual crowning jewel of the full redemption, as the expression of his confidence that Israel will not be redeemed.

And this is connected to the famous verse in Ezra (4:6): "And during the reign of Achashverosh, at the beginning of his reign, they wrote a hateful denunciation against the inhabitants of Yehuda and Yerushalayim."

The authors of the denunciation are identified in Seder Olam Rabbah ch. 29:

"And they hanged the ten sons of Haman, they who wrote denunciation against the inhabitants of Yehuda and Yerushalayim."

According to this, this is the sequence of events: Achashverosh, ecstatic over the abolishment of the building of the Temple, expresses his joy by bringing out the vessels of the Mikdash, and afterwards appoints the authors of the accusation and their father as chief ministers and advisors. But they are not satisfied with stopping the construction of the Mikdash, and in their wickedness they attempt to annihilate Israel.

Furthermore, regarding Achashverosh's royal garments we find: "Rabbi Levi said: He showed them the garments of the High Priest. Here (Esther 1:4) it says 'the splendor of his majesty' and it says there (in Shemot 28:2 regarding the Kohen Gadol) 'And you shall make holy garments for Aharon your brother for honor and splendor.'

Achashverosh's uncompromising determination not to allow the construction of the Mikdash emerges even at a moment of kindness, when he says to Esther (Esther 5:3):

"What do is your (concern) Queen Esther and what is your request? Up to half the kingdom and it will be given to you."

The Talmud (Megillah 15b) explains: "Half the kingdom and not all of the kingdom. And not that which in bisects the kingdom (is in the middle of the world). And what is it? The construction of Beit HaMikdash."  

This is how the Sages see the struggle between Achashverosh and Haman against Mordechai and Esther: not just as a struggle over the right of the Jews to exist, but as the desire to eradicate from the world the Kingdom of Heaven which is expressed by the building of the Temple - G-d's "royal palace." This war was declared against the awakening strength of the approaching redemption, and versus this came HaShem's war against Amalek, and we celebrate this victory on Purim.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 

Fifty Cubits

This is the intention of Pirkei D'Rabbi Eliezer which connects the wood in the house of Haman to Beit HaMikdash, and quoting the verse (Ezra 6:11) which spells out Koresh's decree against whoever will attempt to hinder the building of the Temple: 

"And a decree is issued by me, that any man who will change (hinder) this, a wood (beam) will be torn from his house to hang him upon it, and his house will be turned into a garbage heap."

The height of the beam, fifty cubits, also relates to the Mikdash. By requesting to hang Mordechai on a wood fifty cubits in height, he reveals his desire to reach and corrupt even the fiftieth gate, but he fails and falls, as the Maharal writes in Ohr Chadash p.175:

"When Haman saw his great success, that his power almost reached the 50^th gate, for this (reason) he made himself into an idol, and therefore he said 'make a wood fifty cubits in height' and therefore it says 'and he elevated him above all the ministers' – he elevated him to the number 50 ('all' = כל = 50) and thus he made him an idol. And what is said that Koresh cursed Haman by saying 'a wood (beam) will be torn from his house' means that this power, to prevent the construction of Beit HaMikdash, will be taken away from him. And (you must) understand these things well, and we cannot explain further because these things are very deep."

This intention, according to the Maharal, is expressed even by the name Haman (ה"מ-ן) - its number is 45 (מ"ה).

 And this itself caused Haman's death, 'and therefore death came to him completely.'

The ascent to the fiftieth gate, which is entirely above nature, and even Moshe didn't attain it (at least during his lifetime) is inapproachable for evildoers. And when they attempt to corrupt that aspect, they themselves are harmed, and the explanation to this is that all their power comes from nature and hester panim (the concealment of G-d's presence). But when (power) above nature is revealed, they are nullified.

This too is the source of their great opposition to the construction of the Temple, to which the Divine Presence will return to dwell in Israel, and their kingdom will be nullified.

Eliyahu

Eliyahu HaNavi is the proclaimer of the redemption, he assists and brings the redemption closer. In Megillat Esther, the entire struggle is against the redemption of Israel from the Babylonian exile and the rebuilding of the Temple. Therefore we can understand why Pirkei D'Rabbi Eliezer specifically connects Eliyahu to the indictment against Haman, who erects a fifty-cubit high pole in order to hang Mordechai along with the hope for redemption. Eliyahu intervenes at the most critical moment, which cannot be left in the hands of the king's chamberlains. As the Maharal says in Ohr Chadash p. 194:

"The opinion of the (Talmud) Yerushalmi is that Harvona was Eliyahu of blessed memory, since it is difficult to say that this salvation came about by virtue of Harvona."

And conceivably there is a reason why Eliyahu appeared specifically in the image of Harvona, since his name alludes to the subject of the building of the Temple according to HaMidrash HaTeimani HaAtik (Rimzei Harvona, Remez 4):

"The name Harvona is related to 'har boneh' (builds the mount) since Israel were promised that before the coming of the Moshiach, Eliyahu will appear."

Or, according to the name's plain meaning: harev boneh (builds that which was destroyed) - its construction began by virtue of this act.

In addition to the natural connection between Eliyahu and the redemption, it is likely that there is a special connection to the building of the Temple (and this seems to be the intention of HaMidrash HaTeimani).

If we want we can bring sources from the Tanach, and if we want we can bring sources from the Midrash.

The greatest act of Eliyahu was the event at Mount Carmel, and only after the failure of the prophets of Ba'al did Eliyahu call all of Israel and begin by first building the altar:

"And Eliyahu said to all the nation: come close to me. And all the nation came close to him and he repaired the destroyed altar of G-d and Eliyahu took twelve stones as the number of the tribes of the sons of Ya'akov… and he built of the stones and altar in the name of G-d." (Kings 1, 18:30-32)

Eliyahu does not suffice with the miracle of the fire coming down from Heaven, and he places importance in the nation's taking part in the building of the destroyed altar and sees this as part of his duty. And we can say that his mission in the future, bringing the nation to Teshuva, was derived from the event at Mount Carmel where all said: HaShem is the Lord. And it is likely that the task of building the Mikdash will be entrusted to Eliyahu, just as he repaired the altar on Mount Carmel.

Also when Eliyahu speaks before HaShem in the cave, he mentions the destruction of the altars before the killing of the prophets: "B'nei Israel abandoned Your covenant, they destroyed Your altars and killed Your prophets by the sword."

And if we want to quote from the Midrash, the Tanhuma (Buber) Bereshis 12, as well as the Yerushalmi Brachot 89:

Eliyahu of blessed memory asked Rav: Master, why do earthquakes come to the world? He answered: when the Kadosh Baruch Hu sees that Israel is not separating their Ma'asrot as they should, earthquakes come to the world. Eliyahu of blessed memory said: (by) your life, is that the reason? But this is the main reason: when the Kadosh Baruch Hu looks at His world and sees houses of idolatry standing on their places, securely and tranquilly, and Beit HaMikdash is destroyed, at that moment (He) wants to knock down the world and (so) He shocks it."

Eliyahu's grief over the destruction of the Temple is expressed in this Midrash, perhaps because this (the rebuilding) is his mission.

Eliyahu as the Fighter Against the Wicked

The victory over Haman and his hanging also correspond with Eliyahu's mission, since the task of fighting against the wicked is on his shoulders, whether against the prophets of Ba'al or in the future, as explained in Midrash Tanhuma (Buber) Mishpatim 12:

"The Kadosh Baruch Hu said: in this world I sent an angel before you, and he would annihilate the nations of the world. But in the world to come, Eliyahu of blessed memory, I will send him before you, as it says "Behold I am sending you Eliyahu the prophet before the coming of the great and awesome day of G-d." (Malachi 3:23)

And so it appears from Seder Olam Rabbah ch. 17:

"And in the second year of King Achazziah, Eliyahu was concealed, and will not be seen until the king Moshiach will come and then he will be seen, and will be concealed again and will not be seen until Gog and Magog will come."

And it seems simple that his appearance in the war of Gog and Magog will be for the purpose of destroying the wicked.

The Mission of Eliyahu

The deep meaning can be expressed according to HaRav Charlap in his book MiMa'ayanei HaYishuah part 6, p. 49, in the paragraph: The unification of the two Meshichim:

"The revival of Israel depends on two Meshichim – Moshiach Ben Yosef and Moshiach Ben David… and it is the task of Eliyahu the prophet to connect the two Meshichim and to make the one: 'Behold I am sending you Eliyahu the prophet before the coming of the great and awesome day of G-d and he will return the hearts of fathers to sons, and the hearts of sons to their fathers.' "

In the book of Likutim of Rabbi Moshe David Vali, the student of the Ramchal, part 1 p. 244: The tasks of Moshiach Ben David and Moshiach Ben Yosef are the destruction of the edifice of the kelipot (evil) on one hand, and the building of Kedushah on the other. And this subject is explained, and it is likely that for this reason the alef (in Harvona) turned into heh, to teach about the building which is happening here.

So may we merit to see the Temple built and the sanctuary in its perfection, soon and in our days.