For Moses - The meaning of this verse is, that the Law of Moses, prohibiting these things, was read in the synagogues constantly. As these commands wore constantly read, and as the Jewish converts would not soon learn that their ceremonial law had ceased to be binding, it was deemed to be a matter of expediency that no needless offence should be given to them. For the sake of peace, it was better that they should abstain from meat offered to idols than to give offence to the Jewish converts. Compare 1 Corinthians 8:10-13.Of old time - Greek: from ancient generations. It is an established custom, and therefore his laws are well known, and have, in their view, not only the authority of revelation, but the venerableness of antiquity.
In every city - Where there were Jews. This was the case in all the cities to which the discussion here had reference.
Them that preach him - That is, by reading the Law of Moses. But, in addition to reading the Law, it was customary also to offer an explanation of its meaning. See the notes on Luke 4:16-22.