While residing in Kirtland Elder Reynolds Cahoon had a son born to him. One day when President Joseph Smith was passing his door he called the Prophet in and asked him to bless and name the baby. Joseph did so and gave the boy the name of Mahonri Moriancumer.
When he had finished the blessing he laid the child on the bed, and turning to Elder Cahoon he said, the name I have given your son is the name of the brother of Jared; the Lord has just shown [or revealed] it to me. Elder William F. Cahoon, who was standing near heard the Prophet make this statement to his father; and this was the first time the name of the brother of Jared was known in the Church in this dispensation.
(George Reynolds, “The Jaredites", Juvenile Instructor, 1 May 1892, p. 282 n.))