The Lord gives this advice to Alma to help him understand that those brought before him in judgment who are critical of others are not truly repentant. This is a key for passing correct judgment upon the transgressor. A warning to all of us, it is reminiscent of the word of the Lord to the elders of the church, ye ought to forgive one another; for he that forgiveth not his brother his trespasses standeth condemned before the Lord; for there remaineth in him the greater sin. I, the Lord, will forgive whom I will forgive, but of you it is required to forgive all men (DC 64:9-10).
Spencer W. Kimball
“Remember that we must forgive even if our offender did not repent and ask forgiveness…Do we follow that commandment or do we sulk in our bitterness, waiting for our offender to learn of it and to kneel to us in remorse?…No bitterness of past frictions can be held in memory if we forgive with all our hearts.” (Conference Report, Oct. 1949, pp. 132-3 as taken from Latter-day Commentary on the Book of Mormon compiled by K. Douglas Bassett, p. 237)