Musnad Abu Ya'la al-Mawsili 111:27

Abu Ya'la informed us, he said: It was read to Bishr, Abu Yusuf informed you, from al-Ajalih, from Abdullah ibn Dhakwan, from al-A'raj, that he said: Abdullah ibn Malik ibn Buhaynah informed me that he saw the Messenger of Allah (may Allah bless him and grant him peace) pray at night, and he did not sit in the first two prostrations, so he performed the two prostrations of forgetfulness in their place.