The Book of Oaths (Kitab Al-Aiman)

Muslim :: Book 15 : Hadith 4064

Abu Haraira reported Allah's Messenger (may peace be upon him) as saying: Your oath should be about something regarding which your companion will believe you. 'Amr said: By which your companion will believe you.

Source materials are from the University of Southern California MSA site
Hadith eBooks converted from Imaan Star