Sayyiduna Imran bin Husayn (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) gave the salam after three rak'ahs of the Asr prayer, and then went into his house. Then Sayyiduna al-Khirbaq (may Allah be pleased with him), a man with long hands, stood up and called out: O Messenger of Allah! Has the prayer been shortened? The Messenger of Allah (peace and blessings be upon him) came out angry, dragging his cloak, and asked the people. When they informed him (peace and blessings be upon him), he (peace and blessings be upon him) prayed the rak'ah that had been left out. Then he gave the salam, performed two prostrations, and gave the salam again.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3817