Proverbs 3:8

(8) Navel.—As being the centre, and so the most important part of the body. (Comp. the epithet applied to Delphi, “navel of the earth.”)

Marrow.—Literally, watering: i.e., refreshing. (Comp. Job 21:24.) For the opposite condition, “dryness of the bones, comp. Proverbs 17:22.