What sin did Adam perform by placing the blame on Chavah?
Rashi and Ramban (citing Chazal): Hashem did Adam a favor by giving him Chavah as a helpmate. Blaming Chavah for his sin was the ultimate act of ingratitude 1 - 'Kefuy Tovah' 2 (made worse by the statement "ha'Ishah asher Nasata Imadi", which is intrinsically derogatory - Rashi in Avodah Zarah 5b). 3
Seforno #1: Worse still, he had the Chutzpah to place the blame on Hashem for giving him Chavah in the first place.
Seforno #2: When a sinner is confronted by his sin, the correct thing to do is to confess to having sinned and to do Teshuvah (like David ha'Melech, when rebuked by Nasan ha'Navi), and not to blame someone else.
Gur Aryeh: How is this derived from the Pasuk? Adam could have said simply, 'my wife'. Rather, he shifted the blame onto Hashem, by saying, "the woman that You gave me".
See Torah Temimah, note 7, who discusses the meaning of 'Kefuy Tovah'.
Oznayim la'Torah: It should be noted however, that both Chavah and Adam immediately confessed to having sinned, as opposed to Kayin, who will shortly claim "ha'Shomer Achi Anochi".
Why did Adam eat when Chavah gave to him?
Moshav Zekenim: She hit him until he ate. Before he ate from it, he did not have knowledge to protest. 1
Seforno: Refer to 3:6:3:1 .
If so, why was he punished? Perhaps it is because the sin came through his adding to Hashem's word. I.e. he made Chavah think that Hashem commanded not to touch the tree. (PF)
Hashem asked Adam why he ate. What did he mean with the answer, "the Ishah that you gave to me..."?
Ramban: What Adam meant was that, since Hashem gave him Chavah as a helpmate, he believed that, whatever she advises him must be the correct thing to do. 1
Chochmah u'Musar (Vol. 2, p. 278): Full regret must uproot against the source of sin. Women know to entice their husbands. Adam said, 'I need to uproot the ability to be enticed.'
To which Hashem replied that it was obvious that he was not permitted to follow her advice against Hashem's express command.
