Does a vow take away the reward of charity, and does it have a great reward, or is it disliked?

If a woman vows to donate half of her salary monthly, she is obligated to fulfill it, as the Prophet (peace be upon him) said: "Whoever vows to obey Allah, let him obey Him; and whoever vows to disobey Him, let him not disobey Him." And Allah praised those who fulfill their vows, saying: "They fulfill [their] vows and fear a Day whose evil will be widespread."