seasoned with salt (v.6) — Salt has a twofold purpose; 1) It gives flavor to the discourse and recommends it to the palate. This is the primary idea of the metaphor here, as the word “seasoned” seems to show; 2) It preserves from corruption and renders wholesome. It may be inferred that this secondary application of the metaphor was present to the apostle’s mind here, because of the parallel epistle (Ephesians 4:29), “Let no corrupt communication proceed out of your mouth.” — Wuest, page 235.
know (v.6) = be fully aware
answer each one (v.6) — according to his individual needs