Musannaf Ibn Abi Shayba 28:1146

Waki’ narrated to us, he said: Ma’qal ibn ‘Ubayd Allah al-‘Absi narrated to us, from ‘Umar ibn ‘Abd al-‘Aziz, he said: The *hasir* (the one who is exhausted or the one whose mount is exhausted) should not slaughter (his mount).