I think there is no need to comment on such a
senseless practice. The thing, however, which needs to be kept in mind is that
making religious vows (nazar/mannat) in itself is something which is
discouraged by Islam. It is not a very sound approach to make good deeds
conditional to certain results of the future if they come out be as a person
desires. The Prophet (sws), it is known, never made a vow.
Of course! making vows is not forbidden. In fact, if a
person happens to make one he should go on to fulfil it. The Prophet (sws) has
said that all vows which result in the disobedience of Allah or are against
Islam as well as sense and reason must be broken and must also be atoned for.
This atonement (kaffarah) is a punishment for being irresponsible and is the
same as that of breaking oaths mentioned by the Qur’ān (See 5:89).