Ubaidullah bin 'Umar bin Hafs عبيد الله بن عمر بن حفص بن عاصم · The Book of Oaths and Vows

"The Prophet came to us when we were in the marketplace and said: 'This marketplace is filled with idle talk and (false) oaths, so mix some charity with it.'"

"Whoever swears by a religion other than Islam, telling a lie, will be as he said, and whoever kills himself with something, he will be punished with it in the Hereafter, and there is no vow concerning that which a man does not possess."