Mikeitz (Genesis 41:1-44:17 )
The brothers could not have used an impostor for Benyamin.
In order to force his brothers to return with his beloved younger brother Benyamin, Yosef put one of them in jail and threatened that his freedom would be dependent upon their returning with Benyamin (42:19-20). If Yosef's desire was simply to be reunited with Benyamin, why was it necessary to incarcerate one of the other brothers? As Yosef knew that the famine would continue for many years, wouldn't it have sufficed to inform them that they wouldn't be able to make any further grain purchases unless they return with Benyamin, which would force them to do so?
The Panim Yafos answers that had Yosef done so, the brothers would have been able to hire a random person off the street to escort them to Egypt and claim to be Benyamin. Since they didn't realize that the person they were speaking to was Yosef, there would be no reason for them to think that he would be able to tell the difference, and for him to call them on their deception would require him to reveal his true identity.
Therefore, Yosef implemented an ingenious plan. He imprisoned Shimon and forced him to remain behind in Egypt. Were the brothers to return with anybody but the real Benyamin, Yosef would be able to line up a number of men, including the man they claimed was Benyamin. Were they to return with an impostor, Shimon wouldn't be able to pick out the stranger from the lineup and their ruse would be discovered. As a result, the brothers had no choice but to return with the true Benyamin, who Shimon would be able to recognize, and whom Yosef would finally be able to able to lay his eyes on.
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Why does the Torah, which teaches only what is necessary for all generations to know, record (41:45) that Pharaoh changed Yosef's name to Tzafnas Paneiach?
The Chizkuni and Rabbi Chaim Kanievsky (Taima D'Kra) explain that this information is necessary to answer a very practical question: even if Yosef's brothers didn't recognize him now that he had a beard (Rashi 42:8) and didn't recognize his voice since he was speaking a different language, shouldn't it have been a giveaway when they heard everybody calling him Yosef? In order to prevent this from happening and interfering with His Divine plan, God caused Pharaoh to change his name to one that would disguise his identity.
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At the end of each parsha, a line appears in the Chumash stating how many total verses are in that parsha. Parshas Mikeitz is unique in that the line which is printed at the end of it states not only that it contains 146 verses, but also that it contains a total of 2025 words. As the word count appears at the end of no other parsha, why is it mentioned here?
The Vilna Gaon (Genuzos HaGra) answers that Parshas Mikeitz is almost always read on the Shabbos which falls out during Chanukah. This connection between Chanukah and Parshas Mikeitz is alluded to by the number of words in the parsha - 2025. The numerical value of the word "ner" (candle) is 250, and multiplying by the eight days on which we light candles yields 2000. We begin celebrating Chanukah on the 25th day of Kislev, which when added to the total yields 2025, the exact number of words in Parshas Mikeitz.
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If a person lights Shabbos candles and then realizes (before sundown) that he forgot to light the menorah, the law is that he should appoint an agent who has yet to accept Shabbos upon himself to light the menorah on his behalf. How can this be reconciled with the Talmud (Nazir 12b) which teaches that one may not appoint an agent to do something which he himself cannot do?
The Pri Megadim (Aishel Avrohom 679) answers that in this case, there is no need for the legal appointment of an agent. As long as the person owns the oil and it is burning, he fulfills his mitzvah, and there is therefore no problem that the person who accepted Shabbos is unable to appoint an agent. However, he points out that according to this reasoning, the "agent" should be unable to recite any blessings when lighting the menorah.
However, the Maharam Schick (Even HaEzer 1:120) explains that one is only unable to appoint an agent to perform an action that he cannot do himself if he intrinsically cannot do that action. In this case, he is capable of lighting the menorah and fulfilling the mitzvah, but the tangential problem that he already accepted Shabbos prevents him from doing so, and in such a case, he is able to appoint an agent to do so for him.