Matthew 12:5

Or have ye not read in the law, how that on the sabbath days the priests in the temple profane the sabbath--by doing "servile work." and are blameless?--The double offerings required on the sabbath day (Num 28:9) could not be presented, and the new-baked showbread (Lev 24:5; Ch1 9:32) could not be prepared and presented every sabbath morning, without a good deal of servile work on the part of the priests; not to speak of circumcision, which, when the child's eighth day happened to fall on a sabbath, had to be performed by the priests on that day. (See on Joh 7:22-23).

In this chapter, we have, I. Christ's clearing of the law of the fourth commandment concerning the sabbath-day, and vindicating it from some superstitious notions advanced by the Jewish teachers; showing that works of necessity and mercy are to be done on that day (Mat 12:1-13). II. The prudence, humility, and self-denial of our Lord Jesus in working his miracles (Mat 12:14-21). III. Christ's answer to the blasphemous cavils and calumnies of the scribes and Pharisees, who imputed his casting out devils to a compact with the devil (v. 22-37). IV. Christ's reply to a tempting demand of the scribes and Pharisees, challenging him to show them a sign from heaven (Mat 12:38-45). V. Christ's judgment about his kindred and relations (Mat 12:46-50).

12:5-6 Priests worked on the Sabbath (Lev 24:8-9; Num 28:9-10), and this was not offensive to Pharisees. If the priests’ work for the Temple on the Sabbath is allowed, then certainly Jesus can do the same because he is greater than the Temple (see Matt 4:23; 9:35; 11:2-6, 20-30).