Muhammad bin Hatim Al-Samayn محمد بن حاتم البغدادي - السمين · The Book of Oaths and Vows

The Messenger of Allah said: "There is no vow to commit an act of disobedience and its expiation is the expiation for an oath." Mansur bin Zadhan contradicted him in his wording.

"There is no vow to commit an act of disobedience or with regard to that which the son of Adam does not possess."

"The Prophet saw a man being supported by two others and said: 'What is this?' They said: 'He vowed to walk to the House of Allah.' He said: 'Allah has no need for this man to torture himself. Tell him to ride.'"