Jami` at-Tirmidhi 167
جامع الترمذي#167SahihAbu Hurairah narrated that :Allah's Messenger said: "If it were not that it would be a hardship on my Ummah, then I would have ordered you to delay Isha until the third of the night, or its half
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan Sahih
Zubair Ali ZaiIsnaad Sahih
In-book reference: 2:19