מדרש אויף קהלת 1:16

"I spoke with my heart, saying, 'Behold, I became great, and I accumulated wisdom,' etc." (Ecc. 1:16.) From here they said, the heart sees, the heart listens, the heart speaks, the heart knows, the heart stands, the heart falls, the heart goes forth, the heart cries out, the heart rejoices, the heart becomes comforted. The heart sees: "And my heart saw much wisdom and knowledge." (Ibid.) The heart speaks: "And I spoke with my heart." (Ibid.) The heart knows: "The heart knows the bitterness of its soul." (Prov. 14:10.) The heart listens: "Bestow upon Your servant a heart that listens." (1 Kings 3:9.) The heart stands: "Will your heart stand [firm], will your hands remain strong...?" (Ez. 22:14.) The heart falls: "Let no man's heart (courage) fall from within him." (1 Sam. 17:32.) The heart goes forth: "And he said to him, 'Did my heart (spirit) not go forth...?'" (2 Kings 5:26.) The heart cries out: "Their heart cried out to God." (Lam. 2:18.) The heart rejoices: "Therefore my heart rejoices, and my glory exults." (Ps. 16:9.) The heart becomes comforted: "Comfort, O comfort, my people, says your God. Speak unto the heart of Jerusalem." (Is. 40:1-2.)