- The Malbim writes that they wanted Mordechai hanged in the morning because that is when public executions were performed in order to show the strength of the monarchy.
- The Ben Ish Chai writes that Zeresh was, in effect, telling Haman that Mordechai was in prayer at that time, he wouldn’t be aggravated by the sight of him.
- The Maharal says that morning represents geulah (redemption). This is why the very next verse (Esther 6:1) begins the positive upswing of Megillas Esther.
- R’ Yehonasan Eibshutz quotes the Midrash Abba Guria that Zeresh wanted Mordechai to be killed during the time of Shema. That way, Mordechai would be unable to connect geulah to tefillah (prayer)1, which the Talmud promises would have otherwise protected him (Brachos 9b).
1This is a Halachic concept (Shulchan Aruch Orach Chaim 66:7, Mishnah Berurah ibid., sub-paragraph 33) that forbids any interruption between the morning prayer ending in “ga’al Yisroel” (“Savior of Israel”) and the Amidah.