2 pairs or 7 pairs?

Genesis 6:19-20— “Was Noah supposed to bring two pairs of all living creatures (Genesis 6:19-20), or was he to bring seven pairs of ‘clean’ animals (Genesis 7:2; see also Genesis 7:8,9)?”

Genesis chapter six makes no mention of any ‘clean’ animals, while chapter seven specifically delineates between the clean and unclean animals. Genesis 7:2 says Noah was to bring in seven pairs of ‘clean’ animals and two pairs of every kind of ‘unclean’ animal. It is obvious that there is no discrepancy between the two accounts.

The reason for including seven of the clean species is perfectly evident: they were to be used for sacrificial worship after the flood had receded (as indeed they were, according to Genesis 8:20). Obviously if there had not been more than two of each of these clean species, they would have been rendered extinct by their being sacrificed on the altar. But in the case of the unclean animals and birds, a single pair would suffice, since they would not be needed for blood sacrifice.