After having God speak to Abram about not being afraid, Abram has doubts about how God will provide for him a name sake. God makes a covenant with Abram and it is only God who establishes this. Abram, You or me could never keep a covenant wit God so He exclusively makes one that will be kept. All that is needed is Abram to believe and to obey. For you and I, we would do well by listening to the voice of the Lord (through His word) and then obey His word!