This idiom means that Abraham trusted God even though it did not seemthat he could have a son. Alternate translation: "Even though it seemed impossible for him to have descendants, he believe God" (See: [[rc://en/ta/man/translate/figs-explicit]])
The full promise God gave to Abraham can be made explicit. Alternate translation: "You will have more descendants than you can count" (See: [[rc://en/ta/man/translate/figs-explicit]])