God's promise to bless Abram and also the world through Abram would be fulfilled through a very specific son of Abram and Sarai who had not yet been born. At his advanced age, it all seemed so impossible to Abram, but God gave him a sign to remind him of what he had been promised. Though believing the promise continued to be a challenge, Abram accepted the covenantal sign and continued to hope in the fulfillment of what it signified.