I am the one who is best informed of the time of this prayer, i.e. the night prayer. The Messenger of Allah (ﷺ) used to offer it at the hour when the moon went down on its third night.
Sunan Abi Dawud Book 2, Hadith 29
← Previous Hadith Marthad ibn Abdullah said: When AbuAyyub came upon us to fight the infidels and in those days Uqbah ibn Amir was the Governor of Egypt, he (Uqbah) delayed the sunset prayer. Hence AbuAyyub stood and said: What kind of prayer is this, Uqbah? He said: We were busy. He said: Did you not hear the Messenger of Allah (ﷺ) say: My community will remain well, or he said: will remain on its natural condition, so long as it would not delay the evening prayer until the stars shine brightly just like a network.

Sunan Abi Dawud Book 2, Hadith 28 Next Hadith → We remained one night waiting for the Messenger of Allah (ﷺ) to offer the Isha prayer. He came out to us when one-third of the night has passed or even after it. We did not know whether anything kept him occupied or there was some other matter. When he came out, he said: Are you waiting for this prayer ? Were it not that it would impose a burden on my people, I would normally pray with them at this time. He then gave orders to the mu'adhdhin who declared that the time of the prayer had come.

Sunan Abi Dawud Book 2, Hadith 30