Genesis 15:16

But in the fourth generation they shall come hither again: for the iniquity of the Amorites is not yet full.

But in the fourth generation, [Hebrew, dowr (H1755), or dor (H1755)] - the revolution or circle of human years; an age or generation. [Like genea (G1074), among the Greeks, and soeculum among the Romans, its meaning, as to extent of time, differed at different periods.] In the patriarchal age it denoted a hundred years (cf. Genesis 15:13 with Exodus 12:40). In later ages its signification was more limited, since it is used to describe a period of from thirty to forty years (Job 42:16). And on the ground of this ordinary import borne by the word "generation," a recent writer has founded an objection to the historical truth of this history. But he draws an unwarrantable conclusion; for, since there are only two modes of computing a "generation," the ordinary rate of calculating it at from thirty to forty years, and the patriarchal usage to which, in accordance with Abram's habits of thought, the Divine Revealer accorded His words, it is evident that the "fourth generation" is to be taken in the latter sense, as is distinctly intimated in Genesis 15:13.

They shall come hither again. [In that part of the speech of Stephen (Acts 7:7) where he is quoting this prediction, he adds, kai (G2532) latreusousin (G3000) moi (G3427) en (G1722) too (G3588) topoo (G5117) toutoo (G5129). But these words are not found either in the Hebrew text or the Septuagint. They are supposed by Wolfius to refer to Exodus 3:12.]

For the iniquity of the Amorites is not yet full. The Amorites were so numerous and powerful a tribe in Canaan that they are sometimes named for the whole of the ancient inhabitants, as they are here. The statement implies that there is a progress in the course of sin and vice among nations as well as with individuals, and that, although it be long permitted, by the tolerant spirit of the divine government, to go on with impunity, it will at length reach a culminating point, where, in the retributions of a righteous Providence, the punishment of the sinner, even in this world, is inevitable.