Either to heaven and earth themselves, and so it is a figure called prosopopoeia; or to the inhabitants of them, all angels and men, whom he calls in for witnesses and judges of the equity of his present proceedings. Compare Deuteronomy 4:26 Deuteronomy 31:28, Deuteronomy 32:1. That he may judge his people, to wit, in their presence and hearing.
Related Commentaries of Psalms 50:4
Psalms 50:4
4 He shall call to the heavens from above, and to the earth, that he may judge his people.