Musnad Ahmad 1153:613

Bahz narrated to us, he said: Shu'bah narrated to us, from Qatadah, from Mutarrif, from 'Aishah, that the Messenger of Allah (may Allah bless him and grant him peace) used to say in his bowing (ruku') and his prostration (sujud): "Subbuh, Quddus, Lord of the angels and the Spirit."