Tafsiran Kejadian 15:16: Rashi, Chizkuni, Ramban & Rashbam

ודור רביעי BUT A FOURTH GENERATION — i.e. after they go into exile in Egypt they will be there three generations, and the fourth will return to this land (הֵנָה hither). For He was then speaking to him in the land of Canaan and it was there that He made this covenant, as it is written (v.7) “to give thee this land to inherit it”. Thus it really was: Jacob went down to Egypt. Go and count up his generations: Judah, Perez, Hezron— and Caleb (whose father Jephuneh is identified with Hezron, see Sotah 11b) was amongst those who entered the land of Canaan.

ודור רביעי, “and the fourth generation;” Rashi makes the following calculation concerning this ambiguous statement: the generations mentioned commence with Yehudah, son of Yaakov, (Avraham’s greatgrandson), Peretz, Chetzron, Calev, son of Chetzron already entered and lived in the holy Land. If someone were to raise the point that already Chetzron had taken part in the Exodus from Egypt, i.e. he had been liberated from exile, Yaakov cannot be included as the fist generation, as he had already lived for 130 of his 147 years before taking up residence in Egypt. A different way of making the calculation meant in the above prophecy: “the fourth generation” of which G-d spoke does not refer to the fourth generation of Israelites, but to the fourth generation of the Emorites, [whose sin, as G-d had explained, had not yet reached the point that gave G-d justification to expel them from their homeland, Ed.] The length of a generation of Emorites is considered as being 100 years. Therefore it would take 400 years until G-d’s promise to Avraham could be fulfilled. The Torah, however, did not add the word דור, except for the fact that G-d, when meting out judgment, one does not do so in terms of multiples of hundreds of years, but in terms of generations. [We have examples of this in Exodus 20,5 as well as in Exodus 34,7. Ed.] We also find examples of this in Kings II 10,30. G-d had promised Yehu that even the son of the fourth generation would sit on the throne of the Kingdom of Israel. [The last one, Zecharyah, only ruled for 6 months. Ed.] [The “Kingdom of Israel,” is distinct from the kingdom of Yehudah. Ed.]

AND IN THE FOURTH GENERATION THEY SHALL COME BACK HITHER. After they are exiled into Egypt, they will be there for three generations. And thus it happened; Jacob was exiled into Egypt. Go and reckon his generations: Judah, Peretz, Chetzron, and Caleb the son of Chetzron was amongst those who entered the Land. Thus the language of Rashi. But this is not correct at all.³²⁶Since Chetzron was among those who went down to Egypt (further, 46:12), they were in Egypt for only two generations. And if “the dwelling in a strange land” is to be reckoned as beginning with Abraham, there are seven generations from Abraham to Caleb: Abraham, Isaac, Jacob, Judah, Peretz, Chetzron and Caleb. (Tur.)
The correct interpretation appears to be that the fourth generation refers to the Amorite whose sin will then become full,³²⁷Thus enabling Israel to return and take the land from him. (Tur.) for from the day of the decree He prolonged the time of the Amorite, as He visits iniquity upon the third and fourth generation. Had the Amorites repented of their iniquities He would not have utterly destroyed them. Rather, they would have been a levy of bondservants, or they might have gone elsewhere.