God's covenant with Abraham at age 99 established a pattern of divine faithfulness that extends through generations. This binding agreement included promises to make Abraham the father of many nations, establish an everlasting covenant with his descendants, and give them the land of Canaan. The concept involves mutuality, exclusivity, obligation, and ritual, demonstrated through specific 'I will' promises from God. This pattern of covenant-making continues today through various promises God makes to believers, including salvation, forgiveness, and spiritual growth.