Howbeit, in vain do they worship me
This is the continuation of the citation out of Isaiah, as is also what follows:
teaching for doctrines the commandments of men.
As all these traditions mentioned were such; as washing their hands before they ate bread, and their whole bodies, when they came from the market, or from any court of judicature, or concourse of men, where they had been touched by the common people, and the washing of cups, pots, brazen vessels, and tables, or beds; these they taught the people, and enjoined them the observance of them: instead of instructing them in the doctrines of the Bible, respecting the Messiah, and salvation by him, the right fear, and true worship of God, his ordinances and statutes; wherefore their worship of him, though attended with a great show of sanctity and religion, was a vain thing, a mere empty thing, devoid of life, power, and spirituality, unacceptable to God, and of no real use, profit, and advantage to themselves: it neither issued in the glory of God, nor brought any true pleasure, or solid peace to themselves; and they would find, by sad experience, that their hope of being in the favour of God, and of enjoying eternal happiness on account of it, would prove a vain hope; (See Gill on Matthew 15:9).