Musnad Abu Ya'la al-Mawsili 218:5

Zuhayr narrated to us, Abd al-Samad ibn Abd al-Warith narrated to us, Hashim al-Kufi narrated to us, Kinanah narrated to us, he said: Safiyyah narrated to me that the Messenger of Allah (may Allah bless him and grant him peace) made her manumission her dowry. And that he (may Allah bless him and grant him peace) entered upon her while in her hand were four thousand date pits with which she was glorifying Allah. He said: "You have glorified Allah since I stood over you more than you have glorified [Him]." She said: I said, "Teach me, O Messenger of Allah." He said: "Say: 'Glory be to Allah, to the number of what He has created.'"