How do we know that God does not change His mind?

In 1 Samuel 15:29, it is clearly stated that 'the Strength of Israel will not lie nor repent; for He is not a man that He should repent.' This verse underscores that God is immutable, meaning His nature and purposes do not change. While the biblical language may describe God as 'repenting' in a way that accommodates our understanding, it does not imply that God has regrets or changes course. His will is sovereign and perfect, and He is outside the limitations of time and human emotion, assuring us that His judgments and decrees are unchangeable.