This hadith is reported through another chain, and in it he (peace and blessings be upon him) said: 'Subhanaka rabbana wa bihamdika, Allahumma-ghfir li' (Glory be to You, our Lord, with Your praise; O Allah, forgive me). He would say this in order to act upon the command of the Qur'an.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2561