Colossians 3:15

And let the peace of God rule in your hearts
By "the peace of God" is meant, either the peace believers have with God, which is his gift, and passes all understanding, and flows from a comfortable apprehension of interest in the blood, righteousness, and atonement of Christ; or rather that peace which does, or should subsist among the saints themselves, which God is the author of, calls for, and requires, and encourages in them. The Vulgate Latin, Syriac, and, Ethiopic versions, read, "the peace of Christ"; and so the Alexandrian copy, and some others. This may be said to "reign" in their hearts, when it is the governing principle there; when it restrains the turbulent passions of anger, wrath, and revenge, allays undue heats, moderates the spirits, and composes differences. The metaphor is taken from the judge in the Olympic games, who was the umpire, the moderator, and who determined whose the victory was, and to whom the crown belonged; the apostle would have no other umpire among the saints than the peace of God: and the arguments he uses follow,

to the which also you are called in one body;
the saints in their effectual calling are called to peace by God, who is the God of peace; by Christ, who is the Prince of peace; and by the Spirit, whose fruit is peace; and through the Gospel, which is the Gospel of peace, and into a Gospel state, which lies in peace, righteousness, and joy in the Holy Ghost: and they are not only called to this, but they are called "in one body"; though they are many members, yet they are but one body; and therefore ought to be in peace, and that should bear the sway in them, seeing it is unnatural for members of the same body to quarrel with each other.

And be ye thankful;
which intends either gratitude to men, to fellow creatures, for any service or kindness done by them, especially to the saints, the members of the same body, who are placed in a subservience, and in order to be useful to each other; or else to God, for all spiritual blessings in Christ, and particularly the peace he gives, for the effectual calling, and a place in the body, the church; and "to Christ", as the Syriac version reads, for all those graces which come from him, and strength to exercise them, and for himself, and an interest in him, who is all in all; and a grateful spirit, both for spiritual and temporal mercies, is a very becoming and beautiful one, and is another part of the ornament of a Christian: this last is added to make way for what follows.