How do we know that God is sovereign over His promises?

The narrative in Genesis 17 demonstrates God's sovereignty as He firmly establishes His covenant with Abraham, underscoring His capability to accomplish His will irrespective of human circumstances. God's declaration that Sarah will bear a son, Isaac, occurs years after His initial call to Abraham, emphasizing His control over time and events. Additionally, the mention of Ishmael and the assurance of blessings on him shows God's overarching sovereignty—while His covenant of grace is with Isaac, His concern extends to all humanity, highlighting His benevolence even toward those outside of the covenant. This illustrates a profound respect for God's power and authority in fulfilling His promises.