The Gemara interpreted the expression "two living birds" in . The Gemara interpreted the word "living" to mean those whose principal limbs are living (excluding birds that are missing a limb) and to exclude "treifah" birds (birds with an injury or defect that would prevent them from living out a year). The Gemara interpreted the word "birds" (, "zipparim") to mean kosher birds. The Gemara deduced from the words of , "Every bird (, "zippor") "that is clean" you may eat," that some "zipparim" are forbidden as unclean — namely, birds slaughtered pursuant to . The Gemara interpreted the words of , "And these are they of which you shall not eat," to refer to birds slaughtered pursuant to . And the Gemara taught that repeats the commandment so as to teach that one who consumes a bird slaughtered pursuant to infringes both a positive and a negative commandment.