For the Pharisees, wishing to devour the offerings, instructed sons, when their parents asked for some of their property, to answer them, what thou hast asked of me is corban, that is, a gift, I have already offered it up to the Lord; thus the parents would not require it, as being offered up to the Lord, (and in that way profitable for their own salvation). [ed. note: the words in the parenthesis are not in Theophylact]
Thus they deceived the sons into neglecting their parents, whilst they themselves devoured the offerings; with this therefore the Lord reproaches them, as transgressing the law of God for the sake of gain. Wherefore it goes on, “Making the word of God of none effect through your traditions, which ye have delivered: and many such like things do ye;” transgressing, that is, the commands of God, that ye may observe the traditions of men.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).