Why did Yehudah need to mention that he was a guarantor?
Rashi, Hadar Zekenim: This explains why he is speaking on Binyamin's behalf more than his brothers are. 1
Gur Aryeh (citing Mizrachi): The word "Ki" (because) gives a reason for what was stated above. (Rashi explains that it is the motivation for Yehudah's entire efforts.)
Why did Yehudah say that he is an Arev, "me'Im Avi"?
Malbim: Do not say that now that Binyamin has sinned, I am exempt from Arvus. I was a guarantor to my father!
Yehudah was repeating what he had spoken to his father. Why did he say "l'Avi," and not 'Lecha'?
R. Bechayei, Ha'amek Davar: "L'Avi" includes my Father in Heaven.
Why did Yehudah say that if he does not return Binyamin, he will sin against his father "all days"?
Moshav Zekenim: Yaakov knew that he himself would be punished after death (if Binyamin does not return) - "v'Horadtem Es Seivasi b'Yagon She'olah" (42:38). He would agree to send Binyamin only if Yehudah accepted this punishment (Gehinom) on himself, i.e. Niduy in this world and the world to come. 1
Sha'arei Teshuvah (1:42): Yaakov would not forgive this [so there would be no Kaparah].
Ha'amek Davar: Even though Binyamin did not die, I (Yehudah) am liable due to my Arvus, for I accepted punishment for his sins on myself. Also, Yaakov would not believe that Binyamin was seized for theft. 2
Yehudah had promised Yaakov also, "v'Hitzagtiv Lefanecha" (43:9) Why did he say to Yosef only, "Avi'enu Elecha"?
Moshav Zekenim: Had Yehudah said "v'Hitzagtiv," Yosef would say, 'are you a Navi?! Perhaps [Binyamin] will not still be alive!' But to Yaakov, he said "v'Hitzagtiv," for Sheluchei Mitzvah (to redeem Shimon and bring back food) are not harmed (Pesachim 8b).
QUESTIONS ON RASHI
Rashi writes: "I bound myself tightly with Binyamin, by accepting upon myself excommunication in two worlds (i.e. both this world and the next)." But in Parshas Miketz, Rashi (to 43:9) explains as referring to the world-to-come [only]?
Gur Aryeh (to 43:9): Here, Yehudah needed to explain to the viceroy the full extent of the responsibility that he had taken upon himself. Refer to 43:9:1.2:1.
