Adam Clarke on Proverbs 26:8

As he that bindeth a stone in a sling, so is he that giveth honor to a fool - It is entirely thrown away. This, however, is a difficult proverb; and the versions give but little light on the subject. The Hebrew may be translated, "As a piece of precious stone among a heap of stones, so is he that giveth honor to a fool." Or, As he that putteth a precious stone in a heap of stones. See Parkhurst: but on this interpretation the meaning would rather be, "It is as useless to throw a jewel among a heap of stones to increase its bulk, as to give honor to a fool."

As he that sendith a stoon into a hepe of monee; so he that geveth to an unwiisman wirschip - Old MS. Bible. "He that setteth a foole in hye dignite, that is even as yf a man dyd caste a precious stone upon the galous." - Coverdale. This translator refers to the custom of throwing a stone to the heap under which a criminal lay buried. The Vulgate gives some countenance to this translation: "He who gives honor to a fool is like one who throws a stone to Mercury's heap." Mercury was considered the deity who presided over the highways; and stones were erected in different places to guide the traveler. Hence those lines of Dr. Young: - "Death stands like Mercuries in every way;

And kindly points us to our journey's end."