Commentary for Shabbat 188:17

TO REMOVE IT TO A KARMELIT — Because it (the corpse) was laying in disgrace, or in a burning building, or in the heat (where it may begin to rot); if the problem is moving (muktzeh), he can place a loaf of bread or a child on it (the corpse). (see Shabbat 43b:7)

A PROHIBITION IN THE TORAH — the negative commandment of "you must not deviate" (Deut. 17:11), as it does here.