But he chose the tribe of Judah. The meaning is, that God preferred the tribe of Judah to all the rest of the people, and chose from it a king, whom he might set over all the Israelites as well as the Jews. And he chose the mountain of Zion, appointing a certain spot upon it to be the seat of his sanctuary. That the cause of this choice might not be sought any where else but in God, it is particularly stated that the preferring of mount Zion to all other places, and the enriching of it in such a distinguished manner, proceeded entirely from the free and unmerited love of God. The relative which is here put instead of the causal adverb for; the meaning being, that the sanctuary of God was established there, not for any worthiness of the place, but solely because it was the good pleasure of God. It was proper that this second restitution of the people should be no less free than their first adoption was, when God made his covenant with Abraham, or when he delivered them from the land of Egypt. God's love to the place had a respect to men. From this it follows, that the Church has been gathered together from the beginning, and in all ages, by the pure grace and goodness of God; for never have men been found to possess any intrinsic meritorious claims to his regard, and the Church is too precious to be left to depend upon the power of men.

But chose the tribe of Judah - He chose David of the tribe of Judah as ruler and king; he chose a place within the limits of Judah, to wit, Mount Zion, or Jerusalem, as the place where his worship was to be celebrated. Thus, the ancient prediction in regard to the supremacy of Judah was accomplished. Genesis 49:8-10.
The Mount Zion, which he loved - Which he chose, for which he had an affection. Compare Psalm 87:2.

But chose the tribe of Judah,.... Both to be the seat of kingly power and government, and of religious worship; the latter is chiefly designed. Jerusalem was, at least part of it, in the tribe of Judah: here David, who was of that tribe, dwelt, and Solomon his son, and all the kings of Judah afterwards; here the temple was built, into which the ark of the covenant was put, and whither the tribes went up to worship
the mount Zion, which he loved; where was the city of David; into which the ark was brought when removed from Gibeah, and on part of which the temple was built: the choice of this place, for such a purpose, was from love, Psalm 87:2, it was typical of the church, the choice of which also arises from the everlasting and unchangeable love of God to it.

Chose - For the seat of the ark and of God's worship.