Ibn Juraij reported

I said to Ata': Which time do you deem fit for me to say the 'Isya' prayer, -as an Imam or alone, -that time which is called by people 'Atama? He said: I heard Ibn 'Abbas saying: The Messenger of Allah (ﷺ) one night delayed the 'Isya' prayer till the people went to sleep. They woke up and again went to sleep and again woke up. Then 'Umar b. Khattab stood up and said (loudly)" Prayer." Ata' further reported that Ibn 'Abbas said: The Messenger of Allah (ﷺ) came out, and as if I am still seeing him with water trickling from his head, and with his hand placed on one side of the head, and he said: Were it not hard for my Ummah, I would have ordered them to observe this prayer like this (i. e. at late hours). I inquired from 'Ata' how the Messenger of Allah (ﷺ) placed his hand upon his head as Ibn Abbas had informed. So Ata' spread his fingers a little and then placed the ends of his fingers on the side of his head. He then moved them like this over his head till the thumb touched that part of the ear which is near the face and then it (went) to the earlock and the part of the heard. It (the bind) neither held nor caught anything but this is how (it moved oil). I said to Ata': Was it mentioned to you (by Ibn Abbas) how long did the Apostle (ﷺ) delay it (the prayer) during that eight? He said: I do not know (I cannot give you the exact time). Ali' said: I love that I should say prayer, whether as an Imam or alone at delayed hours as the Messenger of Allah (ﷺ) said that night, but if It is hard upon you in your individual capacity or upon people in the congregation and you are their Imam, then say prayer ('Isha') at the middle hours neither too early nor too late.