Musnad Ahmad 25:1219

'Abd al-Razzaq narrated to us, Ma'mar informed us, from al-Zuhri, from 'Ubayd Allah ibn 'Abd Allah, from Ibn 'Abbas, who said: Sa'd ibn 'Ubadah asked the Messenger of Allah, peace and blessings of Allah be upon him, about a vow that was upon his mother, so he ordered its fulfillment. 'Abd al-Razzaq narrated to us, Sufyan informed us, from Jabir, from al-Sha'bi, from Ibn 'Abbas, who said: The Messenger of Allah, peace and blessings of Allah be upon him, was cupped on the two sides of the neck and between the shoulders. A slave of the Banu Bayada cupped him, and his wage was a mudd and a half. He spoke to his family, so they reduced half a mudd for him. Ibn 'Abbas said: And he gave him his wage, and had it been forbidden, he would not have given it to him.