Rom Romans, chapter Epistle to the Romans, chapter 4
It was because Abraham confidently believed God’s promise to give him many descendants, when there was no physical basis for his hoping that this would happen, that God erased the record of his sins.
Romans 4:17b-22
He was also convinced {very sure} that the thing that God promised, God was able to do. Psa 115:3; Luk 1:37