Musannaf Ibn Abi Shayba 3:6048

Zayd ibn al-Hubab narrated to us, he said: Musa ibn Ubaydah narrated to us, from Qays ibn Abd al-Rahman ibn Abi Sa'sa'ah, from Sa'd ibn Ibrahim, from his father, from his grandfather Abd al-Rahman ibn Awf, who said: I reached the Prophet, may Allah bless him and grant him peace, while he was prostrating. When he finished, I said: "You prolonged the prostration." He said: "I prostrated in gratitude to my Lord for what He has tested me with regarding my nation."