Musnad Ahmad 30:937

Bahz narrated to us, Hammam narrated to us, Qatadah narrated to us, from Bashir ibn Nahik, from Abu Hurairah. Hammam said: I found in my book: from Bashir ibn Nahik, and I do not think it is except from an-Nadr ibn Anas, from Bashir ibn Nahik, from Abu Hurairah, that the Messenger of Allah (may Allah bless him and grant him peace) said: "Whoever prays—meaning the two rak'ahs of the morning—then the sun rises, let him complete his prayer."