Musannaf Ibn Abi Shayba 3:180

Abu Bakr narrated to us, he said: Hafs bin Ghiyath narrated to us, from Ibn Abi Layla, from al-Sha’bi, from Silah bin Zufar, from Hudhayfah, that the Prophet, may Allah bless him and grant him peace, used to say in his bowing: "Glory be to my Lord, the Magnificent," and in his prostration: "Glory be to my Lord, the Most High." I said: "Does he not add 'and by His praise'?" He said: "Yes, if he wishes, three times."