Musannaf Ibn Abi Shaybah 4809 — One who sleeps through Isha and wakes

Ata said, concerning a man who forgot to pray Isha or slept until morning: "He should first pray Isha." Someone asked: "If, by praying Isha, the morning prayer would be missed, then what should he do?" He said: "He should still pray Isha, even if his Fajr prayer is missed."