It is narrated from Sayyiduna Ibn Mas'ud (may Allah be pleased with him) that once the Prophet (peace and blessings of Allah be upon him) led five rak'ahs in the Zuhr or Asr prayer. After finishing the prayer, someone asked: "O Messenger of Allah (peace and blessings of Allah be upon him)! Has there been an increase in the number of rak'ahs of the prayer?" The Prophet (peace and blessings of Allah be upon him) replied: "No." The people said that you have led five rak'ahs. So the Prophet (peace and blessings of Allah be upon him) performed two prostrations of forgetfulness (sahw) and said: "I am also a human being. Just as you remember, I also remember, and just as you forget, I also forget."