Psalms 106:5

That I may see the good of thy chosen
The elect, according to the foreknowledge of God; who are chosen in Christ to holiness and happiness, through sanctification of the Spirit, and belief of the truth unto salvation by him; the vessels of mercy afore prepared unto glory, both of Jews and Gentiles. The "good" of those is not any goodness of their own, for there is none in them naturally; they are by nature no better than others, none are good, nor do good, no, not one: but the goodness of God laid up for them, and bestowed on them; the blessings of goodness with which Christ is preparing for them; all the good things secured for them in a well ordered covenant; which they partake of in time, and to eternity. To "see" these is not to have a superficial, notional, knowledge of them, as hypocrites may have; or a distant view of them, as Balaam, and the rich man in hell; but to have an experience of them, possess them, and enjoy them.

That I may rejoice in the gladness of thy nation;
all the nations of the world are the Lord's; but there is a chosen generation, an holy nation, that is peculiarly his; a nation taken out of a nation, nay, taken out of all the nations that are upon earth: and these have a joy peculiar to them, which foreigners know nothing of, and strangers intermeddle not with; a spiritual joy in the Holy Ghost; a rejoicing in Christ Jesus, in his person, blood, righteousness, and sacrifice, and in hope of the glory of God; and such joy is desirable, a joy unspeakable, and full of glory.

That I may glory with thine inheritance;
the same with his chosen people and nation: for the Lord's people is his portion, and the lot of his inheritance; they are chosen for an inheritance, given to Christ as such, with which he is well pleased, esteeming them a goodly heritage; they are his purchased possession, his jewels and peculiar treasure. These "glory" not in themselves, in their strength and wisdom, their riches and righteousness; but in Christ and in his righteousness, and in what he is made unto them. And the psalmist desires to join with them, and glory in what they did, and in no other; and unite with them in giving glory to God and Christ, now and hereafter, for his salvation, and all good things from him.