Anyone...who traps a wild animal or bird shall spill its blood and
it with earth. (Vayikra 17:13)
When a kosher wild animal or bird is slaughtered, its blood must be
covered, top and bottom, with earth. Covering the blood is a form of mercy
to the life-source of the creature. (Maharsha, Bava Kama 117a).
On the same lines, Ramban (on Vayikra 7:26) mentions three reasons why we
do not eat blood:
• It is considered the life of the creature, so we spare it.
• So that we don’t become like an animal.
• When we bring a korban, we use the blood to atone for us. We don’t eat
that which can benefit us in this unique manner.
One has to recite a blessing before performing this mitzvah: “Al Kisui
HaDam” (Rambam, Hilchos Shechitah 14:1).
The Rambam also teaches (ibid., 15) that the one who slaughters the animal
should perform the mitzvah, but if he fails to do so, an observer has the
mitzvah to step in and do so.
One may not use his foot to cover the blood with earth, rather he should
use his hand or a utensil so that he should not treat it
disrespectfully.... The honor is not for the mitzvah itself, but rather
for the One who commanded us to perform them, Blessed is He.... (Rambam,
Hilchos Shechitah 14:16)