Albert Barnes Commentary Proverbs 26:8

"As one that bindeth a stone in a sling, So is he that giveth honor to a fool." — Proverbs 26:8 (ASV)

That is, "To give honor to the fool is like binding a stone in a sling; you cannot throw it." In each case, you misapply and therefore waste. Others interpret it according to the marginal note: To use a precious stone where a pebble would be sufficient is no less foolish than to give honor to a fool.