Mahmud bin Ghaylan محمود بن غيلان العدوي مولاهم أبو أحمد · The Book on Vows and Oaths

That the Prophet (ﷺ) said: "Whoever takes an oath, and then he sees that something else is better than it, then he should make atonement for his oath and then do it."

"I said: 'O Messenger of Allah! My sister vowed that she would walk to the House barefoot and without Khimar (covering).' The Prophet (ﷺ) said: 'Verily Allah will not do anything with the misery of your sister. She should ride, and cover, and fast three days.'"