Tractate Semachot

A dying man is regarded as a living entity in respect of all matters in the world: he holds [his brother’s wife] tied to the leviratical marriage, he frees [his mother] from the obligation of a leviratical marriage and enables her to eat terumah, and he [may also] disqualify her from eating terumah; he inherits and transmits; if one of his limbs is severed, it is regarded as a limb cut off from the living; if [part of his] flesh [is severed], it is regarded as flesh cut off from the living; and the blood of his sin-offering and guilt-offering is sprinkled for him until the time he dies.

We do not tie up his cheek-bones, or stop up his apertures, or place a metal vessel or anything which chills on his navel; as it is stated, Before the silver cord is snapped asunder and the golden bowl is shattered, and the pitcher is broken at the fountain.

We may not move him, or place him on sand or salt until he dies.