John Gill Commentary Jeremiah 33:25

"Thus saith Jehovah: If my covenant of day and night [stand] not, if I have not appointed the ordinances of heaven and earth;" — Jeremiah 33:25 (ASV)

Thus says the Lord In answer to the above calumny: if my covenant [is] not with day and night; that is, if it should not stand; if it should be broken; or there should be no longer a succession of day and night: [and if] I have not appointed the ordinances of heaven and earth; concerning the course of the sun, moon, and stars, and the influence of the heavenly bodies; and concerning the fruits of the earth, the seasons of the year, seedtime and harvest, summer and winter; if these are not settled and fixed, and do not appear according to appointment and promise.