Musannaf Ibn Abi Shayba 3:2357

Narrated to us Rawh ibn ‘Ubadah, from Ibn Jurayj, from ‘Ata’, regarding a man who forgets the ‘Atamah (Isha) prayer or sleeps through it until it becomes morning. It was said to him: "If he begins with the ‘Atamah, the Subh (Fajr) prayer will pass him by." He said: "Let him begin with the ‘Atamah, even if the Subh prayer passes him by."