Matthew 12:5 - Coke's Commentary on the Holy Bible

Or have ye not read in the law, &c.— He did not mean that these words were to be found in the law, but that they might read in the law, that the priests were obliged on the sabbath-day to perform such servile work in the temple, as, considered separately from the end of it, was a profanation of the sabbath; and yet were guiltless, because it was necessary to the public worship, on account of which the sabbath was instituted. From Numbers 28:9 it appears, that, besides the continual burnt-offerings, the priests were obliged on the sabbaths to sacrifice two lambs extraordinary, by which their servile work was that day double of what it was on the other days of the week. This, though really no profanation of the sabbath, might, according to the common notion of the Jews, be so termed; and therefore, in speaking of it, our Lord calls it so. See Macknight and Calmet.