1)
Why did Moshe and Aharon fall on their faces?
1.
Ramban: When they saw that the people were about to implement their plan to appoint a leader and return to Egypt, they fell on their faces before them 1 to plead with them to retract.
2.
Seforno: When they saw that the people's sin had reached a point of no return, they fell on their faces out of sheer helplessness. 2
3.
Ta'anis, 14b: In order to Daven on behalf of Yisrael.
1
Ramban: As in Shmuel 1, 20:41 and in Bereishis 50:19.
2
Seforno: Like the Sanhedrin in front of Yanai ha'Melech - See in Sanhedrin, 19b.
