al-Zuhri ابن شهاب الزهري‎, محمد بن مسلم · The Book of Oaths

" I did not take oath by (anyone else except Allah) since I heard Allah's Messenger forbidding it. nor did I speak in such terms, and the narrator did not say," on my own behalf or on behalf of someone else".

" He should expiate for (breaking) the vow and do that which is better."