Hazrat Abdullah narrates that the Holy Prophet Muhammad (peace and blessings be upon him) once led a prayer, in which he either added to it or shortened it. When he turned to the people after saying salam, the people said, "O Messenger of Allah! Has a new command regarding prayer been revealed?" He asked, "Why, what happened?" The people replied, "You led such and such a prayer today." The Holy Prophet (peace and blessings be upon him) immediately turned his feet and performed two prostrations. Then he said salam and turned towards the people. Then he said, "If any command regarding prayer had been revealed, I would certainly have informed you. In fact, the reality is that I am also a human being like you; just as you forget, I too can forget. When I forget in prayer, remind me." When any of you makes a mistake in prayer, he should reflect and act upon what seems correct to him. Then, when he says salam, he should perform two prostrations.