Psalms 136:8

The sun to rule by day - Genesis 1:16. Margin, as in Hebrew, for the ruling of the day. That is, to control, as it were, the day; to determine its length - its beginning - its ending - to make it what it is.

For his mercy ... - By all the blessings of day as distinguished from night and darkness - by all that the sun in his daily course does to diffuse life, joy, peace, comfort, happiness on the earth - by all that are warmed by its beams, cheered by its light, guided in labor, guarded from dangers - do we derive an argument for the mercy of God; by all this there is laid a foundation for his praise.