Musannaf Ibn Abi Shayba 3:4805

Waki’ narrated to us, from al-A’mash, from Abu al-Haytham al-Muradi, from Ibn ‘Umar, that a man asked him about that. He said: "Pray, then sleep." Then he said that to him three times. He said in the third time: "Pray, then sleep, and if you sleep, then may your eyes not sleep."