"Thus says the Lord: If you can break my covenant with the day and my covenant with the night, so that day and night will not come at the appointed time, than also my covenant with David my servant may be broken..."
(see vs. 25 too)
Think of how strong God's covenants are if he has a covenant with the solar system to act as it does, and it follows this contract. God made another covenant with us to give us salvation. Our salvation and His love for us are as sure as the sun rising tomorrow morning. Amazing! How weak are our attempts and promises to love in comparison?