Sunan an-Nasa'i 532
سنن النسائي#532SahihIt was narrated that Ibn 'Abbas said:"The Prophet (ﷺ) delayed 'Isha' one night until part of the night had passed. Then 'Umar, may Allah be pleased with him, got up and called out: 'The prayer, O Messenger of Allah! The women and children have gone to sleep.' Then the Messenger of Allah (ﷺ) came out with water dripping from his head, saying: 'This is (the best) time (for 'Isha'), were it not that this would be too difficult for my Ummah
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih
In-book reference: 6:39