Spare the Dying

Necromancy cantrip
Casting time: 1 action
Range: Touch
Target: Living creature within range
Components: V S
Duration: Instantaneous
Classes: Artificer, Cleric
Subclasses: Cleric (Death Domain), Cleric (Grave Domain), Sorcerer (Divine Soul), Warlock (The Undying), Wizard (Theurgy), Mage of Witherbloom (Druid, Warlock)

You touch a living creature that has 0 hit points. The creature becomes stable. This spell has no effect on undead or constructs.