Is the continuation of a vow to slaughter an animal and distribute it to neighbors in specific months, which has lasted for years, considered a bid‘ah (innovation) or is it still obligatory?

If the mother designates specific months for a vow, believing in their particular sanctity or the superiority of making vows during them, this is an innovation (bid'ah), based on the Prophet's (peace be upon him) saying: "Whoever introduces into this matter of ours that which is not from it, it is rejected." However, if her vow in these months is due to her availability or the suitability of the time, then there is no harm in it, and she is obligated to fulfill it, based on his (peace be upon him) saying: "Whoever vows to obey Allah, let him obey Him." Initiating a vow is disliked, due to the Prophet's (peace be upon him) prohibition of it, when he said: "Do not make vows, for vows do not avert anything from destiny; rather, they merely extract something from the miser."