Hajjaj bin al-Minhal حجاج بن المنهال · The Book of Oaths and Vows

"The Messenger of Allah said: 'Whoever swears an oath, then sees something better than it, let him leave his oath, and do that which is better, and offer expiation for it.'"

"The Messenger of Allah forbade vows and said: 'They do not change anything; they are just a means of taking wealth from the miserly.'"

"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."