Musannaf Ibn Abi Shayba 3:205

Abu Bakr narrated to us, he said: Ibn ‘Ulayyah narrated to us, from Ibn Abi ‘Arubah, from Ya’la ibn Hakim, who said: Tawus and ‘Ikrimah said—and I think ‘Ata’ is the third of them—: "When he places his forehead firmly upon the ground, he has fulfilled what is upon him."