According to ancient Egyptians, the hearts of deceased sinners were devoured by Ammit, a fearsome female demon with the head of a crocodile, the torso of a lion, and the hindquarters of a hippopotamus. (Compare to the Chimera.)
Ammit prowled below the scales of justice, waiting for her moment. The jackal-headed god Anubis would conduct the recently dead to the great scales, where he would weigh the deceased's heart against a feather. The feather came from the headdress of Ma'at, the goddess of truth. The ibis-headed god of learning, Thoth, acted as an interrogator of the soul and also recorded the results of the weighing. All nine of the principal gods, called the Great Ennead, observed from their thrones.
If the dead man's heart was lighter than the feather, he was judged sinless and permitted to live forever in a joyful afterlife. But if it sunk, Ammit snatched it up and ate it, and the soul would die the dreaded "second death."
The Egyptian Book of the Dead contains many spells to help the dead soul through all the ordeals it would face in the afterlife. Here is one for dealing with Ammit. Translated by Raymond Faulkner. I have inserted by name in the spell where the name of the deceased person would be. Feel free to copy it and paste your name in. Ideally, we would have this printed on the insides of our coffins, so we would remember what to do when the time came.
From the Egyptian Book of the Dead, Spell 30B: The Judgement of the Dead
O my heart which I had from my mother! O my heart which I had from my mother! O my heart of my different ages! Do not stand up as witness against me, do not be opposed to me in the tribunal, do not be hostile to me in the presence of the Keeper of the Balance, for you are my ka which was in my body, the protector who made my members hale. Go forth to the happy place whereto we speed; do not make my name stink to the Entourage who make men. Do not tell lies against me in the presence of the god; it is indeed well that you should hear!
Thus says Thoth, judge of truth, to the great Ennead which is in the presence of Osiris: Hear this word of very truth. I have judged the heart of the deceased and her soul stands as a witness for her. Her deeds are righteous in the great balance, and no sin has been found in her. She did not diminish the offerings in the temples, she did not destroy what had been made, she did not go about with deceitful speech while she was on earth.
Thus says the Great Ennead to Thoth who is in Hermopolis: This utterance of yours is true. The vinidcated Osiris Sarah is straightforward, she has no sin, there is no accusation against her before us, Ammit shall not be permitted to have power over her. Let there be given to her the offerings which are issued in the presence of Osiris, and may a grant of land be established in the Field of Offerings as for the Followers of Horus.
Thus says Horis son of Isis: I have come to you, O Wennefer, and I bring Sarah to you. Her heart is true, having gone forth from the balance, and she has not sinned against any god or any goddess. Thoth has judged her in writing which has been told to the Ennead, and Maat the great has witnessed. Let there be given to her bread and beer which have been issued in the presence of Osiris, and she will be forever like the followers of Horus.
Thus says Sarah: Here I am in your presence, O lord of the West. There is no wrong-doing in my body, I have not willingly told lies, there has been no second fault. Grant that I may be like the favored ones who are in your suite, O Osiris, one greatly favored by the good god, one loved of the Lord of the Two Lands, Sarah, vindicated before Osiris.