Musannaf Ibn Abi Shayba 3:1601

Abu Bakr narrated to us, he said: Abu Mu'awiyah narrated to us, from al-A'mash, from Ibrahim, from 'Abd al-Rahman ibn Yazid, from Yazid ibn Ziyad ibn Abi al-Ja'd, from 'Ubayd ibn Abi al-Ja'd, he said: 'Ali used to rise in the prayer upon the balls of his feet.