Death usually puts a man in a very serious position, and Burns tips him straight into a joke. In six lines, Satan hears that the antiquary Francis Grose is dying and rushes to collect his soul. At the bedside he finds the bed-posts "groaning" under their "burthen" and backs away, swearing that he'll "want him, ere I take such a damnable load." The central idea is a comic reversal. Grose is kept out of Hell not by virtue, and not by cleverness, but by sheer bulk. The poem never says he is fat. It lets the groaning furniture say so for it, and that indirectness is where much of the fun lies.
The comedy is built on a collision of two kinds of weight. A soul is supposed to be weighed morally, by sin and judgement. Here the weighing is done by a bed. "Burthen" is an old form of "burden," and it carries both senses: a physical load and a spiritual one. "Damnable" does the same double work. It is the Devil's own stock word, yet he uses it as a complaint about heavy lifting. The professional damner ends up grumbling like a porter with a bad back.
"I'll want him" is another neat piece of wording. Here "want" means "do without," so Satan is refusing the commission. The phrase can also be read in its modern sense, as though Satan wants Grose after all and is merely setting a price, which makes the Devil sound like a man haggling over a delivery. Either reading deflates him.
The rhythm gives the poem its speed. The lines gallop in a bouncing, three-beat pattern: "The DEVIL got NOtice that GROSE was a-DYing." The same lilt carries "old Satan came flying," and the interjection "So whip!" makes the Devil's arrival sound like a cartoon dash. The old-fashioned "a-" in "a-dying" and "a-groaning" gives the whole thing the feel of a ballad or a tale told aloud. Then the last line slows down. "Damnable load" is a cluster of heavy syllables, and the voice has to lean on them as if lifting something. The sound of the line mimics its subject.
The rhymes are paired in couplets, and the first two pairs, "dying/flying" and "moaning/groaning," are double rhymes, which are always faintly comic in English. The second pair also links the man and his furniture. Grose "lay moaning" and the bed-posts are "a-groaning," so the sufferer and the wood share one sound and nearly one voice. It is a small bit of personification, and it makes the bed-posts as sympathetic as the patient. The ending is cleverer still. The oath "By G—" is half-hidden by the dash, yet it still rhymes with "load," since anyone reading it fills in the missing letter. Burns shows a polite gap in the text, and the reader supplies the swearing anyway. There is irony too in the Devil of all characters invoking God, just at the moment he is "astonish'd, confounded."
The shape of the poem is that of an epigram: a quick set-up, a build of detail, and a punchline held back for the final line. The first four lines move the Devil from far off to the bedside, and the last two give his verdict. Nothing is wasted, and the joke arrives exactly when the structure says it will.
What makes the poem worth reading is its tone. Laughing at a dying man might seem cruel, and a harsher poet could have made Grose a sinner or a fool. Burns instead calls him "poor Francis" and gives him the one thing nobody expects, a reprieve from Hell. The teasing seems affectionate rather than savage, judging by the way the Devil, not Grose, ends up looking ridiculous. The poem also shows how a very short text can handle big subjects (death, judgement, the body) with a light touch. It takes a familiar figure from folk imagination, the Devil coming to collect, and turns the tradition upside down. In six lines it makes a point that many longer poems miss: the body is a heavy, comic, stubborn thing, and even Satan has limits.