For he hath strengthened the bars of thy gates - He has made thee safe and secure - as if he had given additional strength to the fastenings of the gates of the city. Cities were surrounded by walls. They were entered through gates. Those gates were fastened by bars passed across them, to which the gates were secured. The language here might be applicable to any period, but it is probable that there is particular reference to Jerusalem as made strong in rebuilding it after the return from Babylon.
He hath blessed thy children within thee - The inhabitants, by giving them safety and peace.

He hath strengthened the bars of thy gates - He has enabled thee to complete the walls of Jerusalem. From the former part of the Psalm it appears the walls were then to progress; from this part, they appear to be completed, and provisions to be brought into the city, to support its inhabitants. The gates were set up and well secured by bars, so that the grain, etc., was in safety.

For he hath (i) strengthened the bars of thy gates; he hath blessed thy children within thee.
(i) He not only furnishes his Church with all that is necessary but preserves also the same, and makes it strong against all outward force.

For he hath strengthened the bars of thy gates,.... Of Jerusalem, of Zion the church of God. Gates are for the letting in of persons into the city of our God; which are Christ, faith in him, and a profession of it; see Isaiah 26:1, "bars" are for the security of those that, are in it, and to keep out the enemy: and these, "strengthened", denote the utmost safety of the true members of Christ and his church; who have nothing to fear from their spiritual enemies, sin, law, Satan, the world, death, and hell: God is on their side; Christ is the munition of rocks unto them the Holy Spirit is in them, who is greater than he that is in the world; and angels are guards about them; all which is matter of praise, and a sufficient reason for it;
he hath blessed thy children within thee; multiplied them and made them fruitful, increased the number of them; even the spiritual children of the church, brought forth to Christ by her; born in her, through the ministry of the Gospel; and brought up by her, with the ordinances of it. These in the first times of the Gospel were very numerous, and will be so again in the latter day, like the drops of the morning dew; and are and will be blessed with all spiritual blessings, with pardoning, justifying, adopting, and sanctifying grace, and with eternal life; for which the Lord's name is to be praised.

strengthened . . . gates--or, means of defense against invaders,

Thy gates - Thy strength consists not in thy walls, and gates, and bars, but in his protection.