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 the Zuhr prayer and performed five rak'ahs. Someone asked: "Has there been an addition to the prayer?" The Prophet (peace and blessings of Allah be upon him) said: "No, what happened?" The companions (may Allah be pleased with them) said: "You performed five rak'ahs." Upon hearing this, the Prophet (peace and blessings of Allah be upon him) folded his legs, turned for salam, and performed two prostrations of forgetfulness (sujood as-sahw).