Narrated Sa`id bin Al-Harith: that he heard Ibn `Umar saying, "Weren't people forbidden to make vows?" The Prophet said, 'A vow neither hastens nor delays anything, but by the making of vows, some of the wealth of a miser is taken out."

Narrated `Abdullah bin `Umar: The Prophet forbade the making of vows and said, "It (a vow) does not prevent anything (that has to take place), but the property of a miser is spent (taken out) with it."

Narrated Abu Huraira: The Prophet said, "Allah says, 'The vow, does not bring about for the son of Adam anything I have not decreed for him, but his vow may coincide with what has been decided for him, and by this way I cause a miser to spend of his wealth. So he gives Me (spends in charity) for the fulfillment of what has been decreed for him what he would not give Me before but for his vow."