Jamieson, Fausset and Brown on Isaiah 42:3

3. bruised--"It pleased the Lord to bruise Him" (Is 53:5, 10; Ge 3:15); so He can feel for the bruised. As Is 42:2 described His unturbulent spirit towards His violent enemies (Mt 12:14-16), and His utter freedom from love of notoriety, so Is 42:3, His tenderness in cherishing the first spark of grace in the penitent (Is 40:11).

reed--fragile: easily "shaken with the wind" (Mt 11:7). Those who are at best feeble, and who besides are oppressed by calamity or by the sense of sin.

break--entirely crush or condemn. Compare "bind up the broken-hearted" (Is 50:4; 61:1; Mt 11:28).

flax--put for the lamp-wick, formed of flax. The believer is the lamp (so the Greek, Mt 5:15; Joh 5:35): his conscience enlightened by the Holy Ghost is the wick. "Smoking" means "dimly burning," "smouldering," the flame not quite extinct. This expresses the positive side of the penitent's religion; as "bruised reed," the negative. Broken-hearted in himself, but not without some spark of flame: literally, "from above." Christ will supply such a one with grace as with oil. Also, the light of nature smouldering in the Gentiles amidst the hurtful fumes of error. He not only did not quench, but cleared away the mists and superadded the light of revelation. See Jerome, To Algasia, Question 2.

truth--Mt 12:20 quotes it, "send forth judgment unto victory." Matthew, under the Spirit, gives the virtual sense, but varies the word, in order to bring out a fresh aspect of the same thing. Truth has in itself the elements of victory over all opposing forces. Truth is the victory of Him who is "the truth" (Joh 14:6). The gospel judicial sifting ("judgment") of believers and unbelievers, begun already in part (Joh 3:18, 19; 9:39), will be consummated victoriously in truth only at His second coming; Is 42:13, 14, here, and Mt 12:32, 36, 41, 42, show that there is reference to the judicial aspect of the Gospel, especially finally: besides the mild triumph of Jesus coming in mercy to the penitent now (Is 42:2), there shall be finally the judgment on His enemies, when the "truth" shall be perfectly developed. Compare Is 61:1-3, where the two comings are similarly joined (Psa 2:4-6, 8; Re 15:2, 4; 19:11-16). On "judgment," see on Is 42:1.