Matthew 15:9

But in vain do they worship me
In the Hebrew text it is, "their fear towards me": which is rightly expressed here by "worship"; for the fear of God often intends the whole worship of God, both external and internal: here it only signifies external worship, which these men only attended to. They prayed in the synagogues, read, and, in their way, expounded the books of Moses, and the prophets, to the people, diligently observed the rituals of the ceremonial law, brought their offerings and sacrifices to the temple, and neglected nothing appertaining to the outward service of it; and yet it was all "in vain", and to no purpose; since the heart was wanting, no grace there, they acted from wrong principles, and with wrong views; their worship was merely outward, formal, and customary; and besides, they added doctrines and traditions of their own inventing and devising. The phrase, "in vain", is not in the text in Isaiah: some have thought that it was not originally in Matthew, but inserted by some other hand, to make the sense more complete. Grotius thinks there was a various reading, which is followed by the Septuagint, and the evangelist; and that instead of (yhtw) , "and is", it was (whtw) , the same with (whtl) , "in vain": but there is no need to suppose either of these: Christ, who made this citation, either added it himself for the clearer illustration of the passage, and as being entirely agreeable to the sense of it, and which it required, for the true understanding of it; or he might have in his view another passage of the same prophet, speaking of the same people, and upon the same subject, ( Isaiah 1:11 Isaiah 1:13 ) and from thence take the phrase, and, for explanation sake, join it to the passage here. It follows,

teaching for doctrines the commandments of men;
that is, teaching the people to observe the traditions of the elders, the decrees and determinations of the doctors, as if they were doctrines delivered by God himself; or, instead of the doctrines contained in the Bible, which lay neglected by them, they obtruded on them the orders, and injunctions of men. In the text in Isaiah, are only these words, "taught by the precept of men": and which relate to their fear and worship of God; and which is here interpreted of their teachers teaching them it, and that explained of the commandments of men; as if, instead of (hdmlm) , "taught", it had been read, (Mydmlm) , "teaching". The Jews have no reason to quarrel with this construction and sense, since their Targum paraphrases it thus; "and their fear before me is, (Nyplm Nyrbg tdyqptk) , according to the commandment of men that teach": and a noted commentator ^F3 of their's has this remark on the text, "their fear towards me is" not with a perfect heart, but "by the commandment (Mtwa Mydmlmh Myvnah) , of the men that teach them".