The ear that heareth (hearkeneth to) the reproof of life abideth among the wise (Proverbs 6:23). The reproof, or instruction, of life is that which teaches the true way of pleasing God, which is indeed the only life worth living.
The ear, by synecdoche, is put for the person. One who attends to and profits by such admonition may be reckoned among the wise, and rejoices to be conversant with them. Wordsworth finds a more recondite sense here: the ear of the wise dwells, lodges, passes the night (Proverbs 19:23) in their heart, whereas the heart of fools is in their mouth (Proverbs 14:33).
This verse is omitted in the Septuagint, though it is found in the other Greek versions and the Latin Vulgate.