What made Yosef think that Potifar's wife would care about sinning against Hashem?
Rashi: Because the Bnei No'ach are warned against adultery.
Why did Yosef see fit to first give a logical explanation against having relations with her?
Ramban: Due to the fact that 'Women are light-headed,' and are therefore more prone to sin. 1
Ha'amek Davar: Refer to 39:8:1:2. In the end, these extra words worked against him; refer to 39:18:152:1*.
As we learn from the episode with the snake and Chavah.
Why did Yosef add, "v'Chatasi Le'Elokim!"?
Yerushalmi, Pe'ah 1:1: To teach us that Giluy Arayos belongs to the category of sins that are punished in this world but whose main punishment is reserved for the world to come.
Ohr ha'Chayim #1: I would remove myself from the Source of Neshamos.
Ohr ha'Chayim #2: Even if you will say that you will conceal the matter, and my master will not know, and I will not lose my standing - nothing is concealed from Hashem, so I would lose my good situation!
Ha'amek Davar: Do not say that just like I succeed in everything, Potifar will not find out. If I sin against Hashem, He will not make me succeed!
What other reasons did Yosef add to sinning against Hashem?
Ramban: It would be an act of treachery towards his master, who had placed his faith in him. 1
Ohr ha'Chayim: If I sin, I will lose all the good that I attained.
Malbim: Potifar placed his faith in me, and honored me - "there is no one greater in this house than me"! Ha'amek Davar - Even he is not greater than me in this house! How can I deny such good that he did to me?!
Ha'amek Davar (to 39:8): Potifar trusts me, and does not calculate with me. If I sin, which is like theft, he will suspect me also about his property, and demand many calculations from me!
Ha'amek Davar: He will suspect me, which will be bad for me. A man's jealousy about his wife is great!
What is meant by, "ba'Asher At Ishto"?
Hadar Zekenim (to 39:6): It means [he has withheld you] in marital matters, but he wants me to serve you [in other matters]. 1
It seems that there is a printing mistake, and it should say like this (PF).
QUESTIONS ON RASHI
Rashi writes: "'And I would be sinning unto G-d!' - for Bnei Noach are commanded [to abstain from] forbidden relations." Perhaps Yosef meant that he was supposed to fulfill the Torah (even before it was commanded, as a son of Yaakov)?
Gur Aryeh: When the Avos kept the Torah prior to Matan Torah, without being commanded (Eino Metzuveh, v'Oseh); they received reward for doing so, but to contravene the Torah could not be called a sin. Yosef meant that Arayos of a married woman is certainly a sin, even to his status as a Ben Noach.
