In our Parashah it is related that the Patriarch Isaac went blind in his old age—"and it was when Isaac grew old that his eyesight weakened."¹ Why did his vision weaken? It is not logical to attribute this solely to old age, since at that time a man of Isaac's age was still in full strength, and we do not find others who went blind at that age. Moreover, prior to this, the Torah relates how the Most High blessed him²: "And God blessed Isaac." It is certain that God's blessing would prevent the illnesses and sufferings of old age, let alone a state of blindness, about which our Sages of blessed memory said³ "the blind are considered as though they were dead." Why then did the Patriarch Isaac's eyes weaken?
BLESSINGS TO JAAKOV
Our Sages of blessed memory offer several reasons in this regard. One of them is: "The Most High knew that Isaac loved Esau and would bless him in the future. God said: I will weaken his eyes so that he does not see the one he blesses, so that Jacob may receive the blessings.".
In other words, Isaac's blindness was intended to enable Jacob to receive blessings from Esau. If Isaac had had normal sight, he would have blessed Esau. That is why God weakened his eyes so that he could not see the one he was blessing, and thus Jacob could receive blessings from him.
REVEAL THE TRUTH
But here a simple question arises: to make Jacob worthy of the blessings, there was no need to take away Isaac's sight. Something much simpler could have been done: reveal to Isaac the true nature of Esau, who was actually a wicked man, and then Isaac would have automatically transferred the blessings to Jacob!
In reality, this revelation would not have surprised Itzjak since he knew Esau's wives who served idols.7 It is true that he thought Esau was not guilty of their conduct and could not influence them, but the issue must have aroused some kind of doubt.
He also noted in Eissav Itzjak himself a not entirely smooth conduct, as he said8 "it is not the characteristic of Eissav that the name of Heaven is a custom of being mentioned by his mouth.".
If that were the case, Hashem could have revealed the whole truth about Eisav to him, and then it would not have occurred to him to bless him.
HE IS NOT A WHISTLEBLOWER
The answer is that God does not want to defame anyone, not even the wicked Eisav.
Thus the Gemara tells us that when Achan sinned in the time of Joshua, Joshua asked the Most High, "Who is it that sinned before You?" To which Hashem replied, "Am I Your betrayer?" Therefore, God had no way to prevent Esau from receiving the blessings except by taking away Isaac's sight.
From this we must learn a lesson: If even of Esau the wicked God is not willing to speak Lashon Hara (evil speech), how much more carefully should we be careful not to defame, God forbid, any Jew, since in giving the Torah Hashem said to every Jew, "I am Hashem your God,"10 and gave him the strength so that "I am Hashem" may be "Your God," your strength and vitality.11 Without a doubt, we must be extremely careful not to speak Lashon Hara of any Jew.
(Likutei Sichot Volume 15, Page 211)
GRADES:
1. Our Parashah 27:1 2. Genesis 25:11 3. Pirkei of Rabbi Eliezer Chapter 32 Nedarim 64:6 4. Tanchuma here (8). Rashi on our Parashah 27:1 5. See Rashi's commentary on Vayeshev 37:33: "And why did God not reveal it to him?" 6. And especially that besides all this, Isaac saw that there is something, since Abraham the Patriarch did not bless him (see Rashi's commentary on Genesis 25:11) 7. Rashi's commentary on our Parashah 26:35 8. There 27:1 (from Genesis Rabbah 65:19. Tanchuma Baber on our Parashah 10). But see Ramban and Rashi's commentaries there. 9. Sanhedrin 11:a 10. Exodus 20:2. In the singular (see Ramban Yitro 20:2. Psikta Rabbah in our Parashah 21:6) 11. Likutei Torah beginning of Re'e, and in several places.""