Concern for a mishap
אולי ימשני אבי והייתי בעיניו במתעתע והבאתי עלי קללה ולא ברכה: ותאמר לו אמו עלי קללתך בני שמע בקלי ולך קח-לי
Maybe my father will feel me and I will seem like a deceiver in his eyes, and he will bring upon me a curse and not a blessing. His mother said to him: “Your curse [will be] upon me my son. Listen to my voice, go and take [what I told you to]
The climax of this week’s parsha contains Rivka’s dramatic plot to secure blessings for her son Yaakov, preventing her other son Eisav from receiving them. The blind Yitzchak decided Eisav was more worthy of his final blessings, and requested his talented son go and hunt him some game. While Eisav was away, Yaakov was to enter Yitzchak’s tent, pretend to be Eisav, and receive the blessings himself. Yaakov was reluctant at first, explaining to his mother that the plan was dangerous. Eisav was a very hairy man, and Yaakov was smooth-skinned. What if Yitzchak would feel Yaakov’s arms and realize that he’s not really Eisav? Yitzchak would label Yaakov a deceiver. He would receive his father’s curses, not blessings! His mother reassured him, that no curse would befall him.
There are many nuances to this story, but one question to ask is what exactly was Yaakov’s concern that he’d be labelled a deceiver? Wouldn’t receiving curses be worse? More generally, why was Yaakov so scared he’d be caught? There’s a principle of sheluchei mitzvah einan nizakin, someone in the middle of performing a mitzvah will experience no mishap. He would be in the middle of fulfilling his mother’s command, as well as serving a feast for his father. The merit of such a mitzvah should ensure his success.
It could be that Yaakov had in mind a concept that is discussed in the gemarra. A certain individual was requested by his father to go up a tree and send away a mother bird. Accomplishing this fulfilled two mitzvos. What ended up happening was during this person’s descent from the ladder, he fell and died. The gemarra suggests that the reason he died was because he was thinking about idol worship. While thoughts to transgress the Torah aren’t considered the same as actually transgressing, idol worship is different. Someone who thinks about worshipping idols is considered as if they did.
Eisav went out to hunt animals for his father. This was fulfilling the mitzvah of honoring his father. However, a mishap occurred. Yaakov beat him to receiving the blessings. When Yitzchak realized what had happened, the Torah says that he was horrified. Eisav was occupied with a mitzvah, he should have been successful and received the blessings! The only explanation had to be that Eisav was thinking about idol worship. Because of that a mishap occurred, and the blessings were taken from him.
Yaakov was concerned that something similar would happen to him. Maybe his father would feel his arms and notice they were smooth. He would be caught trying to trick his father, and be labeled a deceiver. Chazal tell us that an idol worshipper is also called a deceiver. If Yaakov would be caught, even though Yaakov was in the middle of performing a mitzvah, his plan to secure the blessings would be a failure. Yitzchak would realize this, and label him a deceiver. Meaning, the only explanation would be that Yaakov was thinking about idol worship. This is why the mitzvah didn’t save him from a mishap. This was Yaakov’s concern about his father.
Still, why was Yaakov concerned he would be caught? He was involved in a mitzvah, and knew that he wouldn’t actually be thinking about idol worship! There should have been no problem. The answer is that he was in fact worried about Eisav. Eisav was fulfilling his father’s wishes by hunting game. This merit would cause that Yaakov’s plan would fail. Yaakov was therefore worried that Yitzchak would feel his arms, and the plan would fail.
However, Yaakov’s mother Rivka knew there was nothing to worry about. She was very aware of Eisav’s evil tendencies. She knew that he was an avid worshipper of idols. There was no doubt that Eisav would be thinking about idols while he completed his father’s mission. This would negate any merit accrued through his mitzvah performance. It would also remove his protection from a mishap occurring. She therefore told Yaakov that any curse would be on her. She was confident that Yaakov would be successful, as he wouldn’t be caught. Yaakov had nothing to worry about.
 Based on Chasam Sofer Al HaTorah to Genesis 27:12
 Genesis 27:12,13
 Pesachim 8b; Yoma 11a; Kiddushin 39b; Chullin 142a
 The Chasam Sofer specifies that Yaakov’s mitzvah was preparing the Pesach and Chagigah offering. This is based on Targum “Yonasan” and Rashi to v. 9. See Pirkei D’Rabbi Eliezer Chapter 32, which seems to be their source. However, see Radal ad. loc. who points out that these sources are saying different things. See also Torah Sheleimah ad. loc. § 43
 Kiddushin and Chullin loc. cit.
 מחשבה רעה אין הקב”ה מצרפה למעשה
 This is learned from Ezekiel 14:5
 Genesis 27:33
 I’m not sure why this would have been Yitzchak’s conclusion. Perhaps Eisav decided not to perform the mitzvah? Yitzchak assumed Eisav was completely righteous. Why assume he transgressed one of the worst transgressions? It’s far less an offense to ignore one’s father’s request
 The Chasam Sofer seems to be learning from the gemarra that the person who fell from the tree and died should have been kept safe by fulfilling the mitzvah, but since he was thinking about idol worship, he died. I’m not sure how he learned the gemarra, as it doesn’t sound like that’s what it’s saying. The gemarra says that this individual died, and it was probably because he was thinking about idol worship. The gemarra then proves from here that there’s no reward for mitzvos in this world, since if there was, his reward for the mitzvah should have prevented him from thinking about idols. Then the gemarra asks why don’t we say sheluchei mitzvah einan nizakin?. Seemingly it’s asking why in fact did he die? The gemarra answers that the ladder was rickety, so it was too dangerous for this principle to apply. Sounds like it if it was a regular ladder, he would have been protected, despite thinking about idol worship
 Sanhedrin 92a
 This is learned from Jeremiah 10:15
 Genesis 27:13. Targum Onkelos ad. loc. sounds like Rivka had a prophecy that Yaakov wouldn’t be cursed. Rashi’s comment to v. 42, based on Bereishis Rabbah 67:9, also seems to indicate that she was a prophetess. This seems to contradict Megillah 14a, which doesn’t list her as a prophetess. Rashi to Genesis 25:23, based on Bereishis Rabbah 63:7, also sounds like she wasn’t a prophetess. This issue is addressed by Maharatz Chayes ad. loc., Torah Sheleimah Chapter 25 § 95, and Rashi HaShalem to Genesis 27:13 § 49. See also Parshegen ad. loc. for a discussion if anything can really be gleaned from Targum Onkelos
 According to this, why then did Rivka put sheepkins on Yaakov’s arms, so that he would appear hairy like Eisav (Genesis 27:16)? Perhaps Yaakov didn’t fully buy into her confidence, and only complied with this compromise