Musnad Ahmad 1153:1146

Sulayman ibn Harb narrated to us, Shu'bah narrated to us, from Qatadah, from Mutarrif, from 'Aishah: That the Prophet, peace and blessings of Allah be upon him, used to say in his bowing (ruku'): "Subbuhun Quddusun, Rabbul-Mala'ikati war-Ruh" (Glorified, Holy, Lord of the angels and the Spirit). He said: And Hisham ibn Abi 'Abdullah said: In his bowing and his prostration.