As mentioned previously, the song “Shoshanas Yaakov” concludes with the words, “v’gam Charvona zachur latov” (“and also Charvona should be remembered for good”).
R’ Meir Zlotowitz explains that Charvona is so well remembered because his advice prevented Haman from speaking in his defense or offering a bribe.
The Ben Ish Chai adds that Esther’s complaint to the kings was rather general. In detailing Haman’s plans, Charvona’s statement was specific.
In Maileetz Yosher, the author suggests that Charvona is praised because Achashverosh changed his mind so often because of the Talmudic (Nedarim 10a) dictum that “evil people are filled with regrets.”
According to the opinion that this manifestation of Charvona was actually Eliyahu dressed up as Charvona, the Dubno Maggid asks why Charvona is praised if Eliyahu was merely disguised as him. He answers that if people borrowed clothes to go to a wedding, they might bring back some delicacies from the wedding as a way to thank the lenders. Eliyahu, too, gave Charvona praise for allowing him to borrow his identity.
The Shaar bas Rabbim explains that Charvona should be praised because when Eliyahu enters a person, he leaves a positive, indelible imprint on that person. This can be seen from a story in the Talmud (Yerushalmi Kiddushin 12:3) in which Rebbi (Yehudah HaNasi) became angry with R’ Chiya, his student. As a form of self-punishment, R’ Chiya stayed away from his teacher. On the 29th day of this self-exile, Eliyahu in the guise of R’ Chiya came to Rebbe and healed him of a certain 13-year-old pain he had. The very next day, R’ Chiya came to apologize, whereupon Rebbe thanked him for healing him. R’ Chiya said, “It was not me,” to which Rebbe responded, “It must have been Eliyahu!” Due to Eliyahu’s borrowing his body, R’ Chiya visited Rebbe the next day because he was inspired and became a better person through his contact with Eliyahu.
The Ginzei HaMelech notes that, in the song, “Shoshanas Yaakov,” we sing about Esther and Mordechai who risked their lives, and about Charvona, who seems to have done very little in comparison. This acts to demonstrate the truth of the Talmud’s (Avoda Zara 17a) statement that “there are those who acquire the world in one moment.” He continues to explain that Charvona’s name is therefore written with a hey to hint to his earning this world, which the Talmud (Menachos 29b) says was created with a hey.
The Dubno Maggid concludes that either way, Charvona must have had some good because the Talmud (Shabbos 32a) says that H-Shem only causes blessing through those who are worthy.