часов ночи

at night (in a time expression)

→ час
phrase Uncommon #25,039
at night (in a time expression) Used after a number to give a time during the night, as in «два часа ночи» (2 a.m.).
RU: Мы работали до двух или трёх часов ночи.
EN: We worked until two or three in the morning.

Я записал, что родился в пятницу в двенадцать часов ночи.

I wrote down that I was born on Friday at midnight.

— История Дэвида Копперфилда (2019)

Том занимался до двух часов ночи.

Tom studied until two o'clock in the morning.

Мы проговорили до двух часов ночи.

We talked until two in the morning.