The specific spell often inscribed on Egyptian heart scarabs is Spell 30, especially the version designated Spell 30B.
In this spell, the deceased appeals to the heart not to testify against its owner during the Weighing of the Heart ceremony. Egyptians regarded the heart as the seat of memory, intelligence, and moral identity, so its testimony could determine the dead person’s fate.
Heart scarabs were large, oval amulets placed over the chest of a mummy. Their inscription was intended to restrain the heart or ensure that it did not contradict the deceased before Osiris and the divine judges. Spell 30B is therefore the most precise technical designation, while “Spell 30” is the commonly accepted shorter answer.
A frequent mix-up is Spell 125, which describes the Negative Confession and the judgment scene itself. Spells 26–30 generally concern protection or preservation of the heart, but 30B became especially associated with heart scarabs.