Albert Barnes Commentary Psalms 74:16

"The day is thine, the night also is thine: Thou hast prepared the light and the sun." — Psalms 74:16 (ASV)

The day is thine, the night also is thine — You have universal dominion. All things are under your control. You have power, therefore, to grant what we desire of you.

Thou hast prepared the light and the sun — He who has made the sun — that greatest and noblest object of creation to the view of man — must have almighty power, and must be able to give what we need.