Is it permissible to fulfill a vow before the occurrence of the vowed event? What is incumbent upon someone who vowed something then found it difficult and recanted? And is the glorification (tasbih) vowed for the sole purpose of fulfilling the vow, or is one also rewarded for it as good deeds?

It is initially makrooh (disliked) due to the hardship it entails, because it does not avert anything, and it extracts (charity) from the stingy. Fulfillment of a conditional vow is not obligatory unless its condition is met, but it is permissible to fulfill it before the condition is met.

The obligation to fulfill a vow is dropped if the one who made the vow is unable to fulfill it, and he must offer an expiation for breaking an oath (kaffarat yamin). However, ordinary hardship does not negate it.

One who fulfills a vow of obedience will be rewarded for performing the act of obedience and for fulfilling the vow.