Mukhtasar Muslim

Narrated by Sayyiduna Ibn Umar (may Allah be pleased with them both) from the Noble Prophet (peace and blessings be upon him) that he (peace be upon him) forbade making vows and said that it brings no benefit (i.e., it does not avert any calamity nor does it change destiny). It is only a means by which wealth is extracted from a miser (i.e., a miser does not usually give charity, but when a calamity befalls, he gives money under the pretext of a vow, and thus the needy benefit).