I command you, all ye my saints, to build a house unto me ... your baptisms for your dead shall not be acceptable unto me; and if you do not these things at the end of the appointment ye shall be rejected as a church, with your dead. Doctrine & Covenants 124:31

Trivia: What man in the Doctrine and Covenants is said to be a perfect man who looked just like his father - so much so, in fact, that they could only be distinguished by their age?