Psalms 50:7

Hear, O my people, and I will speak - God himself is now introduced as speaking, and as stating the principles on which the judgment will proceed. The previous verses are introductory, or are designed to bring the scene of the judgment before the mind. The solemn scene now opens, and God himself speaks, especially as rebuking the disposition to rely on the mere forms of religion, while its spirituality and its power are denied. The purpose of the whole is, by asking how these things will appear in the judgment, to imply the vanity of “mere” forms of religion now. The particular address is made to the “people” of God, or to “Israel,” because the purpose of the psalmist was to rebuke the prevailing tendency to rely on outward forms.

O Israel, and I will testify against thee - In the judgment. In view of those scenes, and as “at” that time, I will “now” bear this solemn testimony against the views which you entertain on the subject of religion, and the practices which prevail in your worship.

I am God, even thy God - I am the true God, and therefore I have a right to speak; I am “thy” God - the God who has been the Protector of thy people - acknowledged as the God of the nation - and therefore I claim the right to declare the great principles which pertain to true worship, and which constitute true religion.