Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates that the Noble Prophet (peace and blessings be upon him) said: "Whoever makes a vow without mentioning its name, its expiation will be the expiation for breaking an oath. And whoever makes a vow concerning disobedience to Allah Almighty, its expiation will be the expiation for breaking an oath. And whoever makes a vow that is beyond his ability (i.e., he cannot fulfill it), its expiation will be the expiation for breaking an oath. And whoever makes a vow in the name of Allah Almighty, which he is able to fulfill, then he should fulfill it."