Nadhr ( Vows)
A nadhr is a religious promise that is allowed to make with Allah. It is not recommended in and of itself, but if done, it must be in Allah’s Name. To do it in someone else’s name is to deify them.
They (are those who) fulfill (their) vows, and they fear a Day whose evil will be wide-spreading. (Insaan 76:7)
This is the only act of worship that is not praiseworthy when done to Allah. It is makrooh (disliked). It is makrooh because it is like a transaction with Allah, but Allah is not in need of your good deeds.
“The Messenger (saw) forbade an-nadhr. He said, ‘An-Nadhr does not make anything happen nor push anything away. Rather it is taken out from the miserly person.” (‘Abdullaah ibn ‘Umar – Related by Al-Bukhari)
“And whatsoever you spend or whatsoever you vow, Allah surely knows it.” (Al-Baqarah, 2:270)
Allah has never praised a nadhr, but if it is done it becomes an obligation.