Musannaf Ibn Abi Shayba 1:1497

Abu Bakr narrated to us, he said: Ibn ‘Ulayyah narrated to us, from Layth ibn Abi Sulaym, from ‘Ata’, that he said regarding the person in a state of major ritual impurity (junub) who reaches a well and does not have a vessel with him: He should lower his garment into the well, then wring it out over his body.