This has two meanings (1) PERSONAL, literally Isaac, Gen. 17:19, and figuratively Christ, Gal. 3:16; (2) GENERAL, meaning “descendants,” it is compared to stars and sand, Gen. 22:17. The former refers to Christ’s heavenly people, Christians, Gal. 3:29, the latter, to Christ’s earthly people, the Jews, Jer. 33:23. Observe it is only the descendants through Isaac that are blessed as Abraham’s seed (Gen. 21:12), so it is only those related to the true Isaac that will receive the blessing, whether they be the stars—the heavenly race, or the sand—the earthly people.