Musannaf Ibn Abi Shayba 21:132

Asbat narrated to us, from ‘Amr ibn Qays, from al-Hakam, from ‘Abd al-Rahman ibn Abi Layla, from Ka’b, from ‘Abd al-Rahman ibn ‘Ujra, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "There are 'mu'aqqibat' (concluding phrases), the one who says them will not be disappointed: Glorify Allah (saying SubhanAllah) after every prayer thirty-three times, praise Him (saying Alhamdulillah) thirty-three times, and magnify Him (saying Allahu Akbar) thirty-four times."