Alma 28

12 While many thousands of others truly ^amourn for the loss of their kindred, yet they rejoice and exult in the hope, and even know, according to the ^bpromises of the Lord, that they are raised to dwell at the right hand of God, in a state of never-ending ^chappiness.

Having presided over a number of funerals, I have observed that mourning results from the separation and sense  of loss that we all have at parting from someone we love. But those who live without hope in the resurrection and in the redeeming power of the atonement of Jesus Christ suffer a different kind of loss. With faith it's possible to feel sad and mourn for the loss of our loved ones and at the same time look forward with hope. The Lord spoke to Joseph Smith and gave this direction (D&C 42):

45 Thou shalt ^alive together in ^blove, insomuch that thou shalt ^cweep for the loss of them that die, and more especially for those that have not ^dhope of a glorious resurrection.

46 And it shall come to pass that those that die in me shall not ^ataste of ^bdeath, for it shall be ^csweet unto them;

47 And they that die not in me, wo unto them, for their death is bitter.