This verse quotes Genesis 22.17, a passage referred to in various parts of the Old Testament and also in Romans 4.19.

Though is an idiomatic equivalent for Revised Standard Version‘s “and him.” Most of the rest of the verse, except as many, comes directly from Genesis 22.17. For languages which do not possess a concessive clause introduced by a conjunction meaning “though” or “even though,” one may express the meaning as “Abraham was practically dead but nevertheless he….” It may, however, be important to indicate that the expression was practically dead is figurative; for example, “was, as it were, almost dead.”

The word came is not strictly a translation of the UBS Greek text, which means “there were born”; this text is followed by other common language translations and Revised Standard Version. The expression from this one man came as many descendants as may be expressed as “this man had as many descendants as,” “this one man produced as great a lineage as,” or “the people who descended from this one man were as many as.”

The comparison of the descendants of Abraham with the number of stars in the sky or grains of sand on the seashore is a kind of literary hyperbole or exaggeration, and these comparisons are to be understood as such. The statement as many as the numberless grains of sand on the seashore may be expressed as “as many as the grains of sands on the seashore which cannot be counted” or “… which no one can count.”

Quoted with permission from Ellingworth, Paul and Nida, Eugene A. A Handbook on The Letter of the Hebrews. (UBS Handbook Series). New York: UBS, 1983. For this and other handbooks for translators see here .