Genesis 7:2-3

"Of every clean beast thou shalt take to thee seven and seven, the male and his female; and of the beasts that are not clean two, the male and his female: of the birds also of the heavens, seven and seven, male and female, to keep seed alive upon the face of the earth."

Right here is where the critics start screaming contradiction! They assert that this is from a different source, and that another source to which they ascribe Genesis 6:20 mentions only "two of every sort." The very next verse (Genesis 6:21), however, stressed that "food of every sort" was also to be taken into the ark; and, if as seems likely (though disputed by some) that animal flesh had been a source of food long prior to the flood, then the multiple pairs of clean beasts and fowl were inherently included previously in God's revelation that ample food supplies were to be taken aboard. So where is the contradiction? Even if their use as food is denied, this verse cannot logically be viewed otherwise than as supplemental instruction. It is altogether reasonable to view this passage as merely a detail "not mentioned,"[2] earlier.