Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) led us in the Asr prayer, and in the fourth rak'ah he (peace and blessings be upon him) stood up (without sitting), until he (peace and blessings be upon him) led us in a fifth rak'ah as well. It was said: O Messenger of Allah, you (peace and blessings be upon him) have led us in five rak'ahs. So he (peace and blessings be upon him) faced the qiblah, said the takbir and performed two prostrations.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 9800