The caution about thoughtless speaking would certainly apply in making vows. Solomon stated: “Whenever you vow a vow to God, do not hesitate to pay it, for there is no delight in the stupid ones. What you vow, pay.

Eccl. 5:4-6.

No one is under any obligation to make a vow to God; it is a spontaneous act. That is why there is a need to be very careful not to speak rashly when making a solemn promise to God. Were a person to hesitate to fulfill his vow, he would be acting as a stupid one, that is, one who is morally defective, untrustworthy in word.