Musnad Ahmad 529:13

Ali ibn Ishaq narrated to us, Abdullah—meaning Ibn al-Mubarak—narrated to us, Thawr ibn Yazid narrated to us, from Khalid ibn Ma'dan, from Jubayr ibn Nufayr, from Muhammad ibn Abi Umayrah, and he was one of the companions of the Prophet, may Allah bless him and grant him peace, who said: "If a servant were to fall upon his face from the day he was born until he died of old age in the obedience of Allah, he would consider that [deed] insignificant on that Day, and he would wish to be returned to the world so that he could increase in reward and recompense."