Parashas Shemos
וַיְהִ֥י בַדֶּ֖רֶךְ בַּמָּל֑וֹן וַיִּפְגְּשֵׁ֣הוּ ה׳ וַיְבַקֵּ֖שׁ הֲמִיתֽוֹ׃
And it was on the way, at the lodging-place, that Hashem encountered him and sought to kill him.
Torah Temimah points to baraisa — Nedarim 31b–32a (verified).
ויהי בדרך במלון — תניא, אמר רבי: חס ושלום שמשה רבינו נתרשל מן המילה, אלא כך אמר: אמול ואצא – סכנה היא\ldots
English: “And it was on the way at the lodging-place” — it was taught, Rabbi said: Heaven forbid that Moshe our teacher was negligent about circumcision; rather he reasoned: If I circumcise and then set out, it is dangerous\ldots
Custom
Chazal defend Moshe from the charge of negligence and explain the episode as a conflict of duties resolved by the angelic encounter.