The Doctrine and Covenants/Section 129

Instructions given by Joseph Smith, Nauvoo, Illinois, February 9, 1843. History of the Church 5:267.

are two kinds of beings in heaven, namely: Angels, who are resurrected personages, having bodies of flesh and bones—

For instance, Jesus said: Handle me and see, for a spirit hath not flesh and bones, as ye see me have.

Secondly: the spirits of just men made perfect, they who are not resurrected, but inherit the same glory.

When a messenger comes saying he has a message from God, offer him your hand and request him to shake hands with you.

If he be an angel he will do so, and you will feel his hand.

If he be the spirit of a just man made perfect he will come in his glory; for that is the only way he can appear—

Ask him to shake hands with you, but he will not move, because it is contrary to the order of heaven for a just man to deceive; but he will still deliver his message.

If it be the devil as an angel of light, when you ask him to shake hands he will offer you his hand, and you will not feel anything; you may therefore detect him.

These are three grand keys whereby you may know whether any administration is from God.