4 Blessed are they that mourn: for they shall be comforted.
President Harold B. Lee said:
“To mourn, as the Master’s lesson here would teach, one must show that ‘godly sorrow that worketh repentance’ and wins for the penitent a forgiveness of sins and forbids a return to the deeds of which he mourns. [See 2 Corinthians 7:10.] It is to see, as did the Apostle Paul, ‘glory in tribulations . . . : knowing that tribulation worketh patience; and patience, experience; and experience, hope’ (Romans 5:3–4). You must be willing ‘to bear one another’s burdens, that they may be light.’ You must be willing to mourn with those that mourn and comfort those that stand in need of comfort (Mosiah 18:8–9). When a mother mourns in her loneliness for the return of a wayward daughter, you with compassion must forbid the casting of the first stone. . . . Your mourning with the aged, the widow and the orphan should lead you to bring the succor they require. In a word, you must be as the publican and not as the Pharisee. ‘God be merciful to me a sinner.’ [See Luke 18:10–13.] Your reward for doing [this] is the blessedness of comfort for your own soul through a forgiveness of your own sins.”
(Teachings of Presidents of the Church: Harold B. Lee , 201–2.)