הלכה על במדבר 16:22

Nefilat Apayim also expresses man’s shame before God. After the Amida, in which we addressed God’s greatness and set all our requests before Him, we are ashamed to show our faces. How did we dare stand before Him in prayer? So we fall down on our faces. Nefilat Apayim also conveys our sorrow as we repent of our sins; we are so anguished that we cannot lift our faces (see Rabbeinu Baḥya on Bamidbar 16:22).