Source: SRD

Gentle Repose

2nd-level necromancy (ritual)  - Clr, Wiz

Casting Time: 1 action

Range: Touch

Components: V, S, M (a pinch of salt and one copper piece placed on each of the corpse's eyes, which must remain there for the duration)

Duration: 10 days

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.

Open Game License v1.0a Copyright 2000, Wizards of the Coast, Inc.

System Reference Document 5.0, Copyright 2016, Wizards of The Coast, Inc.; Authors Mike Mearls, Jeremy Crawford, Chris Perkins, Rodney Thompson, Peter Lee, James Wyatt, Robert J. Schwalb, Bruce R. Cordell, Chris Sims, and Steve Townshend, based on original material by E. Gary Gygax and Dave Arneson.
dxContent.com and dxContent spell database filtering tools copyright Brian Dunn, 2016