1 In that day shall this song be sung in the land of Judah; We have a strong city; salvation will God appoint for walls and bulwarks.   2 Open ye the gates, that the righteous nation which keepeth the truth may enter in.   3 Thou wilt keep him in perfect peace, whose mind is stayed on thee: because he trusteth in thee.   4 Trust ye in the LORD for ever: for in the LORD JEHOVAH is everlasting strength:

      To the prophecies of gospel grace very fitly is a song annexed, in which we may give God the glory and take to ourselves the comfort of that grace: In that day, the gospel day, which the day of the victories and enlargements of the Old-Testament church was typical of (to some of which perhaps this has a primary reference), in that day this song shall be sung; there shall be persons to sing it, and cause and hearts to sing it; it shall be sung in the land of Judah, which was a figure of the gospel church; for the gospel covenant is said to be made with the house of Judah, Heb. viii. 8. Glorious things are here said of the church of God.

      I. That it is strongly fortified against those that are bad (v. 1): We have a strong city. It is a city incorporated by the charter of the everlasting covenant, fitted for the reception of all that are made free by that charter, for their employment and entertainment; it is a strong city, as Jerusalem was, while it was a city compact together, and had God himself a wall of fire round about it, so strong that none would have believed that an enemy could ever enter into the gates of Jerusalem, Lam. iv. 12. The church is a strong city, for it has walls and bulwarks, or counterscarps, and those of God's own appointing; for he has, in his promise, appointed salvation itself to be its defence. Those that are designed for salvation will find that to be their protection, 1 Pet. i. 4.

      II. That it is richly replenished with those that are good, and they are instead of fortifications to it; for the inhabitants of Jerusalem, if they are such as they should be, are its strength, Zech. xii. 5. The gates are here ordered to be opened, that the righteous nation, which keeps the truth, may enter in, v. 2. They had been banished and driven out by the iniquity of the former times, but now the laws that were made against them are repealed, and they have liberty to enter in again. Or, There is an act for a general naturalization of all the righteous, whatever nation they are of, encouraging them to come and settle in Jerusalem. When God has done great things for any place or people he expects that thus they should render according to the benefit done unto them; they should be kind to his people, and take them under their protection and into their bosom. Note, 1. It is the character of righteous men that they keep the truths of God, a firm belief of which will have a commanding influence upon the regularity of the whole conversation. Good principles fixed in the head will produce good resolutions in the heart and good practices in the life. 2. It is the interest of states to countenance such, and court them among them, for they bring a blessing with them.

      III. That all who belong to it are safe and easy, and have a holy security and serenity of mind in the assurance of God's favour. 1. This is here the matter of a promise (v. 3): Thou wilt keep him in peace, peace, in perfect peace, inward peace, outward peace, peace with God, peace of conscience, peace at all times, under all events; this peace shall he be put into, and kept in the possession of, whose mind is stayed upon God, because it trusts in him. It is the character of every good man that he trusts in God, puts himself under his guidance and government, and depends upon him that it shall be greatly to his advantage to do so. Those that trust in God must have their minds stayed upon him, must trust him at all times, under all events, must firmly and faithfully adhere to him, with an entire satisfaction in him; and such as do so God will keep in perpetual peace, and that peace shall keep them. When evil tidings are abroad those shall calmly expect the event, and not be disturbed by frightful apprehensions arising from them, whose hearts are fixed, trusting in the Lord, Ps. cxii. 7. 2. It is the matter of a precept (v. 4): "Let us make ourselves easy by trusting in the Lord for ever; since God has promised peace to those that stay themselves upon him, let us not lose the benefit of that promise, but repose an entire confidence in him. Trust in him for ever, at all times, when you have nothing else to trust to; trust in him for that peace, that portion, which will be for ever." Whatever we trust to the world for, it will be but for a moment: all we expect from it is confined within the limits of time. But what we trust in God for will last as long as we shall last. For in the Lord Jehovah-Jah, Jehovah, in him who was, and is, and is to come, there is a rock of ages, a firm and lasting foundation for faith and hope to build upon; and the house built on that rock will stand in a storm. Those that trust in God shall not only find in him, but receive from him, everlasting strength, strength that will carry them to everlasting life, to that blessedness which is for ever; and therefore let them trust in him for ever, and never cast away nor change their confidence.