In vain do they worship me is quite clearly expressed in Good News Translation, “It is no use for them to worship me.” “The worship they do has no value,” “Their worship does not accomplish anything,” or “They may as well give up their worship” also express the meaning.

Teaching may need an indirect object such as “other people.”

Teaching as doctrines translates a Hebrew idiom in which both nouns originate from the same root. In Isaiah, from which the quotation is taken, doctrines describe the laws and teachings which God had given his people, thus the basis for Good News Translation: “they teach … as though they were my laws.”

Precepts of men (Good News Translation “man-made rules”) are the rules and regulations that originated from human sources. The sentence may then be “They teach other people to follow man-made rules as though they were my laws.” Bibel im heutigen Deutsch, 1st edition attains a somewhat dramatic effect in its rendering of the clause: “for they teach laws which they themselves have thought up.”

Since verse 7 ends with “… prophesy of you, when he said,” it may be more natural to shift to a second person in verses 8-9: “You people … because you teach laws that you yourselves have created.”

Quoted with permission from Newman, Barclay M. and Stine, Philip C. A Handbook on the Gospel of Matthew. (UBS Handbook Series). New York: UBS, 1988. For this and other handbooks for translators see here .