Ramban

‘BESHAGAM’ (FOR THAT ALSO) HE IS FLESH. It is as if beshagam were written beshegam with a segol under the shin. And Rashi explained: “This quality is also in him, that he is only flesh, and yet he is not humble before Me. What would he do if he were made of fire or some hard substance.” This explanation has neither rhyme nor reason. Rabbi Abraham ibn Ezra explained that G-d said, “My spirit will not abide in man forever because of this violence and also because man is flesh, and when he reaches a certain age he disintegrates.” Ibn Ezra thus understands the verse as if it said, gam beshehu basar (also because he is flesh). But what need is there for stating this contention when it is known that they were but flesh. and death had been decreed on them, as it says, For dust thou art, and unto dust shalt thou return? The correct interpretation appears to me to be that G-d said: “My spirit shall not abide in man forever because man also is flesh as all flesh that creepeth upon the earth in the forms of fowl and cattle and beast, and it is not fitting that the spirit of G-d be within him.” The purport is to state that G-d made man upright to be like the ministering angels by virtue of the soul He gave him. But he was drawn after the flesh and corporeal desires; he is like the beasts that perish, and therefore the spirit of G-d will no longer be sheathed in him for he is corporeal and not godly. However, He will prolong for them [this withdrawal of spirit] if they repent. The sense of this verse is thus similar to [the verse in Psalm 78]: So He remembered that they were but flesh, a wind that passeth away, and cometh not again.