Musnad Ahmad 1016:12

'Abd al-Razzaq and Ibn Bakr narrated to us, they said: Ibn Jurayj narrated to us, Ibn Shihab informed me, that 'Abd al-Rahman ibn Hurmuz al-A'raj informed him, from 'Abd Allah ibn Buhaynah—and he was one of the companions of the Prophet, may God bless him and grant him peace—that he informed him: That the Messenger of God, may God bless him and grant him peace, prayed two rak'ahs for them, then he stood up and did not sit during them, so the people stood up with him. When he had prayed the final two rak'ahs, the people waited for his taslim. He said "Allahu akbar" and prostrated, then he said "Allahu akbar" and prostrated, then he performed the taslim.