(a) It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) led the Asr prayer and gave the salam after two rak'ahs. Sayyiduna Dhu al-Yadayn (may Allah be pleased with him) said: O Messenger of Allah, have you forgotten, or has the prayer been shortened? The Messenger of Allah (peace and blessings be upon him) said: "None of that has happened." He said: Something has happened? The Messenger of Allah (peace and blessings be upon him) turned to the people and asked: "Is Dhu al-Yadayn right?" The Companions (may Allah be pleased with them) said: Yes, O Messenger of Allah. So he (peace and blessings be upon him) completed the remaining two rak'ahs and gave the salam, then after the salam performed two prostrations while sitting.
(b) In one narration it is: "The Messenger of Allah (peace and blessings be upon him) led us in prayer."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3910