Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) gave the salam after praying two rak'ahs, so Dhu al-Yadayn (may Allah be pleased with him) said: "O Messenger of Allah, has the prayer been shortened, or have you forgotten?" The Messenger of Allah (peace and blessings be upon him) said: "Is Dhu al-Yadayn telling the truth?" The people said: "Yes." So the Messenger of Allah (peace and blessings be upon him) stood and led the other two rak'ahs, then gave the salam, then said the takbir and prostrated like his usual prostrations or somewhat longer, then raised his head, and said the takbir and performed the second prostration likewise, then raised his head.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3904