Uqba bin 'Amir al-Juhayni · The Book of Oaths and Vows

"Do not make vows, for a vow does not have any impact on the Qadar. Rather it is just a means of taking wealth from the miserly."

"Whoever vows to obey Allah, let him obey Him, and whoever vows to disobey Allah, let him not disobey Him."

"O Messenger of Allah! I want to give all my wealth in charity for Allah and His Messenger." The Messenger of Allah said to him: "Keep some of your wealth for yourself; that is better for you."