Wonders Before the Entire Nation:

The Chida zt'l (Sefer Nachal Kedumim) quotes Rav Shlomo Astruk zt'l as saying that Moshe told Hashem, "You promised me that I would do wonders before the entire creation, the likes of which have never been seen before (Shemos 34:10). Now is the time to make this 'new creation' in front of the entire nation by creating a new thing and opening the mouth of the earth."