Parashas Shemos · Passuk 4:26
Chabad.org — English translation + Rashi
Torah Temimah points to Nedarim 32a (verified).
Sefaria — Exodus 4:26
Sefaria — Nedarim 32a
E-Daf — Nedarim 32a
English: “And He released him” — R’ Yehudah bar Bizna expounded: When Moshe our teacher delayed the circumcision, Anger and Wrath came and swallowed him, leaving only his feet.
On the daf / in context: See the cited source for the full section.
Custom
Chazal describe the angelic attack as having consumed Moshe except for the feet, the site of the delayed mitzvah.