Sayyiduna Abdullah bin Buhaina Asadi (may Allah be pleased with him), who was an ally of Banu Abdul Muttalib, narrates: The Prophet Muhammad (peace and blessings be upon him) stood up during the Zuhr prayer at the point when sitting was obligatory upon him. When he completed the prayer, before saying the salam, he performed two prostrations of forgetfulness while sitting. The people also performed two prostrations along with him. This was in place of the sitting which he had forgotten. (Imam Ibn Hibban, may Allah have mercy on him, says:) The fact that the Prophet (peace and blessings be upon him) stood up at the place where he was supposed to sit for the first tashahhud, and the people stood up behind him at that time, and the Prophet (peace and blessings be upon him) did not object to their action, is a clear statement that the first sitting (tashahhud) in prayer is not obligatory.