"Lay not, we pray, upon us, etc." Aaron began to ask of him that he forgive them concerning their offspring, and he prayed on behalf of his sister. And therefore it is said, "wherein we have done foolishly, etc." — [as it is said] "the princes of Zoan have become fools, etc." (Isaiah 19:13).
Aaron Pleads for Miriam and Prays Over His Sister
Midrash Aggadah, Numbers 12:11
אל נא תשת עלינו וגו'. התחיל אהרן מבקש ממנו שימחול להם על זרעם והתפלל על אחותו, ולכך נאמר אשר נואלנו וגו', [כמו שנאמר] נואלו שרי צוען וגו' (ישעיה יט יג):