Musnad Ahmad 3958

It was narrated that ‘Abdullah bin Mas'ood said: The Messenger of Allah (ﷺ) prayed five rak'ahs, in Zuhr or ‘Asr, and when he finished, it was said to him: O Messenger of Allah, has something been added to the prayer? He said: “No." They said: But you prayed five. So he did the two prostrations of forgetfulness, then he said: “I am only human, I remember as you remember and I forget as you forget."