In Mormonism, the oath of vengeance (or law of vengeance) was an oath that was made by participants in the endowment ritual of The Church of Jesus Christ of Latter-day Saints (LDS Church) between about 1845 and the early 1930s, in which participants vowed to pray that God would avenge the blood of the prophets Joseph Smith and Hyrum Smith, who were assassinated in 1844 by a mob.

Incorporation into the Nauvoo Endowment

The oath of vengeance was an addition made to the Nauvoo endowment under the direction of Brigham Young by 1845 in the Nauvoo Temple, soon after the 1844 death of Joseph Smith. Participants agreed to be bound by the following oath:

You and each of you do covenant and promise that you will pray and never cease to pray to Almighty God to avenge the blood of the prophets upon this nation, and that you will teach the same to your children and to your children’s children unto the third and fourth generation.

“The prophets” referred to Joseph and Hyrum Smith, who were killed in 1844 by a mob while in jail in Carthage, Illinois. “This nation” referred to the United States.

The oath entered the endowment at a time when many Mormons hoped for retribution for the deaths of Joseph and Hyrum Smith. At least one member of the LDS First Presidency understood the oath to include a personal obligation that, “if he had ever met any of those who had taken a hand in that massacre he would undoubtedly have attempted to avenge the blood of the martyrs.”However, other Mormons understood the oath to require only prayer for God’s vengeance, and not any obligation to take vengeance personally.

The prayer to which endowed Mormons obligated themselves took place, in at least some cases, as part of the Mormon prayer circle ceremony, which was also part of the endowment, but was often performed separately. ¹