창세기 39:9의 주석

וחטאתי לאלהים AND SIN AGAINST GOD — The “Sons of Noah” (בני נח) were subject to the command which forbade immorality (Sanhedrin 56b).

AND I SHALL SIN AGAINST G-D. The Sons of Noah²²⁵See Note 113 above. were commanded concerning forbidden relations. This is Rashi’s language.
This is correct. It is only due to the feminine lack of knowledge that he first told her that the act would constitute a betrayal of his master who trusted him, and following that he added that it also involves a sin against G-d.
It is possible to further explain the verse, And I shall sin against G-d, by this betrayal, since “it would be a matter of great evil consequence which would be accounted to me as a sin against G-d since His eyes are upon the faithful of the land,²²⁶Psalms 101:6. and no traitor dare come before Him.” Joseph spoke the truth. However he did not mention the prohibition of the illicit relation²²⁷According to this interpretation. because he spoke in language suitable to women.

כי אם אותך באשר את אשתו, the only restrictions imposed upon me in this house concern the inviolable marital relations between you and my master, your husband.

באשר את אשתו, "inasmuch as you are his wife." Joseph meant that Potiphar had not placed his wife out of bounds to Joseph in so many words; the matter was understood because of her status.

איננו גדול בבית הזה, there is no one in this house who is superior to me in rank except you who are out of bounds to me inasmuch as you are my master’s wife; how could I abuse the trust placed in me by my master?

וחטאתי לאלוקים, “I would commit a sin against G’d.” Rashi explains that basic legislation about incestuous relations including adultery applied universally, not only to Jews. Nachmanides writes that he finds it difficult that Joseph mentioned the sin of adultery against his own master Potiphar, which is secondary, before mentioning the sin against G’d which is primary. He answers this problem by saying that women do not perceive matters in that order. They relate first and foremost to their visible masters, their husbands, and are only marginally concerned with their sins against the Creator, who remains invisible both to them and to their husbands. There is also another way of answering the manner in which Joseph described the sin of giving in to the allure of Mrs. Potiphar. He did not refer to the aspect of illicit sex at all directly, other than saying that he would be committing a great wrong against G’d’s law, without implying that she would be a party to that sin. According to that approach, the words הרעה הגדולה, “the great evil,” would modify the words וחטאתי לאלוקים.

איך אעשה הרעה הגדולה הזאת וחטאתי לאלוקים , “and how could I commit such a great wrong and sin against the Lord?” He explained that indulging in sex with his master’s wife would be wrong on two counts. Not only would it be an act of betrayal against his employer but it would also be a grievous offense against G’d. This is similar to the wording used by the High Priest Eli when he rebuked his sons in Samuel I 2,25: “If a man sins against a man, the Lord may pardon him [after he has served the penalty decreed by a human tribunal, Ed.]; but if a man sins against G’d who can obtain pardon for him?“

וחטאתי לאלקי׳, abgesehen von der Schlechtigkeit gegen deinen Gatten, ists ja auch, wie jede Unsittlichkeit, ein Verbrechen gegen Gott. — חטא. Es ist von Wichtigkeit, den Begriff der Sünde nach dem hebräischen Sprachgedanken zu ergründen, da sich daraus zugleich der Begriff des Gegensatzes, der des sittlichen Lebens ergibt. Im Deutschen heißt Sünde das zu Sühnende, ein Begriff, der in חטא nicht ursprünglich liegt. Wir wagen die Verwandtschaft von חטא mit חתה hervorzuheben. חתה: etwas aus seinem gehörigen Kreis herausnehmen, insbefondere aber: brennende Kohlen aus dem Feuer nehmen. Es ist nun nicht unmöglich, dass הטא ebenso heiße: irgend eine unserer Beziehungen jenem Feuer, dem Feuerstrahle jenes Elementes entziehen, das eigentlich unser ganzes Wesen fassen, wecken, durchläutern und beleben soll. Die Kohle, die ich aus dem Feuer nehme, erlischt. So lange irgend eine meiner Kräfte von jenem göttlichen Feuer beherrscht ist, wird sie leben und das erreichen, wozu sie bestimmt ist. Überlasse ich aber irgend eine Beziehung meines Wesens diesem Feuer nicht, so wird sie: Sünde. Wir sind berechtigt, das zur Beherrschung unseres ganzen Wesens bestimmte Element als "Feuer" zu denken. Nennt sich ja das Göttliche selber אשרת ,אש אוכלת. Ihm sollen wir stets ganz hingegeben sein, und so lange sind wir ohne Schlacken, das göttliche Feuer leuchtet stets und stets in uns und durch uns, wir sind ׳לחם אשה ד: Nahrung des Göttlichen auf Erden. Sobald etwas diesem Feuer entfällt, wird es dunkel, schlecht. Ist das Sinnliche nicht Träger des Göttlichen, nicht קדוש, wird es viehisch: קָדֵש. Was sich der Glut des Göttlichen entzieht, verfällt der Glut der Leidenschaft. Heißt aber חטא: etwas dem Herde des göttlichen Feuers entziehen, das dadurch dunkel, unerleuchtet, undurch- glüht von dem Feuer wird, das es durchglühen sollte: so begreifen wir, wie sich das ganze מעשה קרבנות als symbolische Wiederherstellung des durch חטא gestörten Verhältnisses in buchstäblichstem Sinne darstellt. Wenn unser הטא nichts anderes war, als dass unser הלב וכליות sich nicht als Nahrung dem göttlichen Feuer überlassen, resp. hingegeben haben: so ist die Wiederherstellung eben nichts anderes, als dass wir sie dem göttlichen Feuer wieder übergeben. Unser ganzes Wesen נפש, gehört Gott an, und als Konsequenz davon, alle unsere Glieder, איברים, Seinem Feuer, נתינת אברים על גבי האש ist reine Konsequenz von נתינת דם על המזבח. — (Siehe auch Kap.13, 13.)

וחטאתי לאלוקים, “and I would commit a sin against G-d;” even if the matter will remain concealed from human beings, G-d sees everything.

הרעה הגדולה הזאת, to repay good with evil.

כי אם אותך באשר את אשתו; these words lend support to the words of the Midrash which saw in the words כי אם הלחם a euphemistic reference to Potiphar’s wife. It is also possible that Potiphar had warned Joseph specifically against getting involved with his wife because he was so handsome. There was no need for the Torah to spell out such a prohibition

ואיך אעשה הרעה הגדולה, "how could I possibly commit such a great evil?" By doing so I would lose everything I have achieved.

להיות עמה, in seclusion.

ואיך אעשה הרעה הגדולה הזאת, to sleep with his wife and to betray his trust? Furthermore, this would not only be a grievous wrong against my master, but it would also be a sin against G’d Who commanded man certain rules of sexual behaviour. (we explained these rules in connection with Genesis 2,24 on ודבק באשתו)

Furthermore, I would create an unbridegable gap to the holy roots of my soul seeing that adultery is forbidden to Gentiles as well as to Jews. This is what Joseph meant when he said "I would sin against G'd."

Furthermore, by mentioning that he would commit a sin vis-a-vis G'd Joseph already countered Mrs Potiphar's argument that her husband did not need to know about their liaison and that therefore Joseph did not stand to lose anything. Joseph attributed his present status to the help of G'd. He would certainly forfeit G'd's help if he became guilty of adultery.