And ye suffer him no more to do ought for his father, or his mother. According to the Jewish canons (w), if a man vowed a thing which is contrary to a command, he was obliged to keep his vow, and break the command: thus, if a man vowed that his father or his mother should never receive any benefit from what he had, but that his substance was as "Corban", or as any thing devoted to divine service, he was obliged to keep his vow; nor was he allowed after this to do any thing for his father, or mother, however poor or helpless they might be; unless he applied to a wise man to revoke his vow, or to give him liberty to do it; for he could not do it of himself, as wicked as it was; and though he might heartily repent of it, and was ever so willing to make it null and void: and though a dissolution it by a wise man was allowed of, yet hereby they set up their own power and authority against God, and his law; they did not rescind the vow, because it was contrary to the command of God: for notwithstanding its being contrary to the command of God, it was to be observed, though to the breaking of that, unless loosed by a wise man, at the man's request; whereby they established their magisterial power and authority, without any regard to the honour and glory of God; and therefore what follows, is justly observed by our Lord; See Gill on Matthew 15:5.
(w) Maimon. Hilch. Nedarim, c. 3. sect. 1.