Laws in our land can be (and are) changed. Rules in school and at work can be (and are) changed. Amendments can be (and are) made to the Constitution. Just when you think something is firmly set as a code of regulation or conduct, someone goes and changes it.
Aren’t you 
glad that the Bible says, “Forever” (not temporary or fluctuating or volatile), “O Lord, Your word is settled in heaven” (Psa. 119:89). What does it mean that God’s Word is settled? The ESV has “firmly fixed.” God’s Word is NOT going to change! Jesus said, “My words will by no means pass away” (Matt. 24:35). Peter affirms, “…The word of God…lives and abides forever…the word of the Lord endures forever” (1 Pet. 1:23, 25).
When God says something, when God commands something, when God promises something, when God guarantees something, IT IS SETTLED! His Word will not change! He will not change it! You can build upon it and act upon it with absolute assurance!