Gentle Repose (Ritual)

(a pinch of salt and one copper piece placed on each of
the corpse's eyes, which must remain there for the
duration)
You touch a corpse or other remains. For the
duration, the target is protected from decay and
can't become undead.
The spell also effectively extends the time limit
on raising the target from the dead, since days
spent under the influence of this spell don't
count against the time limit of spells such as
raise dead.