Get out the microscope, because we’re going through this poem line-by-line.
No farther seek his merits to disclose,
Or draw his frailties from their dread abode,
(There they alike in trembling hope repose)
The bosom of his Father and his God.
- Don't try to find out anything more about the dead speaker's good points.
- And don't try to dig up any dirt on his bad points, or frailties, either.
- Why not, you ask? Both his good and his bad points are in "repose," or resting, hoping for eternal life, in heaven with God. That's why not.