'Vow' in the Bible

After remaining a considerable time longer in Corinth, Paul took leave of the brethren and set sail for Syria; and Priscilla and Aquila were with him. He had shaved his head at Cenchreae, because he was bound by a vow.

so do this which we now tell you. We have four men here who have a vow resting on them.

and they incur disapproval for having broken their original vow.