Why does Rashi explain that Avimelech was the only one who might have slept with Sarah?
(26,10) “And Avimelech said: What is this that you have done to us? One of the people nearly slept with your wife, and you would have brought upon us guilt.”
Rashi explains that the phrase “one of the people” means the most prominent one of the people - the king. But how does Rashi know this - why can’t the posuk simply mean any one of the people?
But we can explain that it must refer to the king because of Yitzchok’s implausible claim that Rivkah was his sister. Surely nobody would believe that Rivkah was the daughter of Avrohom and Sarah since people did not even believe that Yitzchok was the offspring of Avrohom. They believed that Sarah conceived from Avimelech, because Avrohom and Sarah had been childless so many years and yet not long after she had been taken by Avimelech she gave birth to Yitzchok. So why would anyone believe that Avrohom and Sarah had given birth to Rivkah thirty-seven years after the birth of Yitzchok (it was announced to Avrohom at the binding of Yitzchok who was then thirty-seven that Rivkah had been born)! Thus they surely would have suspected that Rivkah was really Yitzchok’s wife, and that he was only claiming that she was his sister out of fear of being killed.
But Yitzchok thought that even though everybody else might not believe that she was his sister, Avimelech would believe him. Because Avimelech knew for sure that Sarah had not conceived from him but from Avrohom through a miracle, and therefore it was quite possible that Rivkah was also born from them through a miracle. Therefore, because he was afraid that Avimelech might kill him for the sake of his wife he said that she was his sister.
That is why Rashi writes that “one of the people” can only refer to the king, since he was the only one who might have been tempted to sleep with Sarah.
If Yitzchok had a doubt about the identity of the person that he was about to bless, why did he not wait and clarify the situation?
(27,22) “And Ya’akov drew near to his father Yitzchok, and he felt him, and he said: The voice is the voice of Ya’akov and the hands are the hands of Eisav. And he did not recognize him because his hands were hairy like the hands of Eisav, and he blessed him.”
Behold, Yitzchok seems to have had a doubt about the identity of the person that he was about to bless, and if so, why did he bless him? He should have waited until he was no longer in doubt, since, as the Alshich writes, he never intended to bless Ya’akov in this world. Even more problematic is that the posuk says that “he did not recognize him because his hands were hairy like the hands of Eisav, and he blessed him”, which seems to imply that he ignored the voice and gave the blessing solely on the basis of his hands!
But we can explain that Yitzchok was afraid that Ya’akov might come and trick him, as he in fact did. So what did he do to forestall this possibility? He figured that if Ya’akov was going to try to trick him into thinking that he is Eisav, he would change his voice and speak harshly like the voice of Eisav. Therefore he instructed Eisav that when he returns from hunting to receive the blessing he should change his voice and speak gently like the voice of Ya’akov. Thus, if the one coming for the blessing spoke like Eisav, he would know for sure that it was Ya’akov.
But Rivkah knew about Yitzchok’s plan through prophetic vision, as we see from an earlier posuk “And Rivkah spoke to Ya’akov, saying (לאמר): Behold, I heard your father speak to Eisav your brother, saying” (27:6). The Alshich asks why the posuk writes the word “saying” twice, but we can explain it according to the well known rule that wherever the Torah writes an expression of דיבור it connotes a harsh way of speaking, and wherever it writes an expression of אמירה it connotes a gentle way of speaking.
Hence, the posuk means that “Rivkah said to her son Ya’akov, לאמר” - she told him to speak gently and not to change his voice from how he normally speaks. And why did she tell him to do this? Because “behold, I heard your father speaking to your brother Eisav, לאמר” - he told Eisav that he should speak gently. Therefore if you change your voice and speak harshly like Eisav, he will realize that you are Ya’akov.
Thus, when Ya’akov came before Yitzchok he did not change his voice, and therefore Yitzchok confidently said “the voice is the voice of Ya’akov” - that is one sign that this is Eisav, “and the hands are the hands of Eisav” - that is another sign, and so “he blessed him” - because, on the contrary, he had no doubt in the matter!