Midrasch zu Dewarim 28:57

(Ib. b) Rabbin said: "What does the passage (Ez. 12, 3) But thou, O son of man, prepare for thyself vessels for going into exile, mean? This refers to a candle, a dish (Fol. 41) and a blanket." (Deut. 28, 57) For want of everything. Said Rabin b. Abba: This means without a light and without a table." R. Chisda said: "It means without a wife." R. Shescheth said: "It means without a servant." R. Nachman said: "It means without knowledge." While in a Baraitha it was explained to mean without salt or fat. Abaye said: "We have a tradition that none could be called poor, except one who is poor in knowledge." In the land of Israel they used to say: "Whoever has this (knowledge) has everything, but whoever has not this (knowledge), what has he? Whoever buys [knowledge,] what else is he in need of, but he who does not buy [knowledge] what availeth him other purchases?"