Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates: The Messenger of Allah (peace and blessings be upon him) delayed the Isha prayer so long that the one who prays had prayed, the one who wakes had woken, the sleepers had slept, and those who pray tahajjud had prayed tahajjud. Then he (peace and blessings be upon him) came out and said: "Were it not that I would burden my Ummah, I would have ordered them to pray this prayer at this time," or he said something similar.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13424