Flesh; which here notes either,
1. The corruption of their natures, which was perpetually inclining them to sin, and consequently exposing them to God's wrath, which must needs have consumed them utterly and speedily, if God had let loose his anger upon them. See the same argument used to a like purpose Genesis 8:21. Or rather,
2. The frailty or infirmity of their natures, as the next clause interprets this; which is such, that if I should not restrain my wrath, I should quickly cut off the body of this wicked people, and their children with them, whom I have promised to carry into Canaan, Numbers 14:31. A wind that passeth away, and cometh not again; that are quickly cut off; and when once they are dead, they never return to this life.