Midrash for Chullin 141:15

נאמרה כאן בהמה טמאה ונאמר להלן בהמה טמאה מה להלן טומאת קדש

To deduce the following: It says here unclean cattle,<span class="x" onmousemove="('comment',' Lev. V, 2: If anyone touch any unclean thing whether it be the carcass of an unclean beast or the carcass of unclean cattle . . and be guilty. In atonement for the guilt committed Scripture prescribes the bringing of a sin-offering, the nature of which varies according to the means of the sinner.');">⁶</span>

Sifrei Devarim