Musannaf Ibn Abi Shayba 3:889

Waki' narrated to us, he said: Al-A'mash narrated to us, from 'Abdullah ibn Murrah, from Masruq, who said: 'Abdullah ibn Mas'ud led us in the Dhuhr prayer when the sun had passed its zenith. Then he said: "This—by the One besides whom there is no god—is the time for this prayer."