創世記 27:1 註釋：Rashi, Rashbam, Radak & Sforno

ותכהין HIS EYES WERE DIM through the smoke raised by these women in offering incense to idols (Midrash Tanchuma, Toldot 8). Another explanation is: When Isaac was bound upon the altar and his father was about to slay him, at that very moment the heavens opened, the ministering angels saw it and wept, and their tears flowed and fell upon Isaac’s eyes which thus became dim (Genesis Rabbah 65:10). Another explanation is: They became dim just in order that Jacob might receive the blessings (Genesis Rabbah 65:8).

ותכהינה עיניו, due to old age, as we find in Samuel I 3,20 when the eyesight of the High Priest Eli failed due to old age.

ויהי כי זקן, the word זקן is a verb in the past tense. The Torah relates that Yitzchok kept on aging until his eyesight was badly impaired. Yaakov experienced a similar problem; (48,10) In fact most people experience the problem of failing eyesight in their old age. In some instances this is a sudden phenomenon, in others it is a phenomenon experienced gradually. In the case of Yitzchok he was struck with this affliction more than 20 years before he died. He misinterpreted the onset of this phenomenon considering it as foreshadowing that his death would occur soon. In the event he was proven wrong. However, this is what prompted him to call in Esau at this time to bestow his blessing upon him before his death. Perhaps this failure of his eyesight at a premature time was one of the afflictions with which the righteous are sometimes afflicted. It may be that the reason why the Torah bothers with telling us this detail is to inform us that G’d subjects some of the righteous to some afflictions in this life in accordance with His wisdom. Some commentators attribute Yitzchok’s premature blindness to the smoke of the incense burned by his daughters-in-law to their respective deities. (quoted by Rashi).