Albert Barnes on Matthew 12:18

My servant. That is, the Messiah, the Lord Jesus, called a servant, from his taking the form of a servant, or his being born in a humble condition, Php 2:7 and from his obeying or serving God. See Heb 10:9.

Shall shew judgment to the Gentiles. The word judgment means, in the Hebrew, law, commands, etc., Ps 19:9, 119:29,30. It means the whole system of truth; the law of God in general; the purpose, plan, or judgment of God, about human duty and conduct. Here it means evidently the system of gospel truth, the Christian scheme.

Gentiles. All who were not Jews. This prophecy was fulfilled by the multitudes coming to him from Idumea and beyond Jordan, and Tyre and Sidon, as recorded by Mk 3:7,8.