Abdullah bin Murrah narrates from Ibn Umar (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) forbade vows and said: "A vow does not avert anything; it is only a means by which wealth is extracted from the miser."
(b) In the narration of Khallad: "Wealth is extracted by it from the miser."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النذور / 20103
Abu Hurayrah (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) said: "A vow does not bring the son of Adam closer to anything that Allah has not decreed for him; rather, the vow coincides with the decree, and by it wealth is extracted from the miser which the miser did not intend to give."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النذور / 20104