Rest of their bones, and soul’s delivery (line 8)
How does that soup commercial go again? Mmm...Death! Good for the body! Good for the soul! Here, the traditional religious distinction between body ("bones") and soul appears. The body gets rest, and the soul gets freedom. Everybody wins!
One short sleep past, we wake eternally, And death shall be no more; (lines 13-14)
What is the speaker more afraid of: the sheer terror and pain at the moment of death, or the possibility that he might not exist in any form after it? The comfort that death is a "short sleep" suggests that he is more afraid of non-existence.