Musnad Ahmad 1034:122

Bahz narrated to us, Hammad narrated to us, ‘Abd al-Malik ibn ‘Umayr narrated to us, a cousin of Hudhayfah narrated to me, from Hudhayfah, who said: I stood beside the Messenger of Allah (peace and blessings of Allah be upon him) one night, and he recited the seven long surahs in seven rak'ahs. He said: When he raised his head from bowing, he would say, "Allah hears those who praise Him" (Sami' Allahu liman hamidah), then he would say, "Praise be to Allah, the Possessor of the Kingdom, the Might, the Pride, and the Greatness." His bowing was approximately the same length as his standing, and his prostration was approximately the same length as his bowing. He finished his prayer, and my legs were nearly broken.