Siman 549

(106.) They told me that once he spoke much about the verse [Proverbs 23]: "Buy truth and do not sell it." And he raised the difficulty that the verse warns not to sell — then from whom will anyone buy? And how is it possible that the verse first warns "buy truth" to buy truth — and afterwards warns "do not sell" — that no one should sell? If so — from whom will one buy? And he spoke much about this — but I did not merit to hear the matter.