Mujahid bin Jabir مجاهد بن جبر · The Book of Oaths and Vows

"The Messenger of Allah came to a man who was being supported by two others and said: 'What is the matter with him?' It was said: 'He vowed to walk to the Ka'bah.' He said: 'Allah does not benefit from his torturing himself.' And he told him to ride."

"The Messenger of Allah said: 'Whoever swears an oath and says: "If Allah wills, then he has made an exception."'"

"Sulaiman said: 'I will certainly go around to ninety women tonight, each of whom will bear a child who will fight in the cause of Allah.' It was said to him: 'Say: If Allah wills' but he did not say it. He went around to them but none of them bore a child except for one woman who bore half a person." The Messenger of Allah said: "If he had said: 'If Allah wills,' he would not have broken his…