Musnad Ahmad 986:0

Narrated to us by Hisham ibn Sa'id, who said: Narrated to us by Muhammad ibn al-Muhajir, from al-Walid ibn 'Abd al-Rahman al-Jurashi, from Jubayr ibn Nufayr, from Nu'aym ibn Hammar al-Ghatafani, that he heard the Messenger of Allah (ﷺ) say: "Allah the Exalted says: 'O son of Adam, do not fail to perform four rak'ahs for Me at the beginning of the day, and I will suffice you for the rest of it.'"