For I the Lord do not change; therefore you, O children of Jacob, are not consumed.
God is constant and for that we should be thankful. He does not change. He is. He always "is". He is faithful and true even as our lives may be chaotic and our commitments fade in and out. He is a covenant keeping, faithful God even when His people are not.
These words written to Israel by the prophet Malachi were a reminder to a people whose commitment to God wavered, that God does not change in His concern for them. Specifically, Israel failed to bring tithes to the temple, a failure God was pointing out strongly to them (see Malachi 3:8-9). But God was still offering mercy to them. They would not be consumed. He wanted them to return to Him in repentance to find mercy and grace (Malachi 3:7). God's mercy made sure they were not consumed (what their sins deserved) and His grace brought them back to Him with blessings when they repented.
You Who are the same yesterday, today, and forever, receive my own confession. Like Israel my commitment can waiver. May my heart be soft to hear Your call to return when that is the case. I fail, but You forgive, and for that I am unworthy yet grateful.