Albert Barnes Commentary Proverbs 31:26

"She openeth her mouth with wisdom; And the law of kindness is on her tongue." — Proverbs 31:26 (ASV)

Law of kindness - The words that come from the lips of the true wife are as a law giving guidance and instruction to those who hear them; but the law is not proclaimed in its sterner aspects, but as one in which “mercy tempers justice,” and love, the fulfilling of the law, is seen to be the source from which it springs.