Midrash su Ecclesiaste 11:10

Raba said again: "A young scholar is like a seed lying under a hard clod which, when it has once sprouted, grows fat." Raba also said: "If a young scholar gets angry, it is the [zeal for the] Torah that excites him, for it is said (Jer. 23, 29) Is not thus my word like the fire saith the Lord?" R. Ashi said: "A scholar who is not as firm as iron cannot be considered a scholar; for the end of that passage reads: And like a hammer that shivereth the rock. What you derive from that passage." remarked R. Abba unto R. Ashi, "we infer from the passage here: It is written (Deut. 8, 9) A land whose stones are iron. Do not read it, Ab'neha (its stones), but read it, Boneha (its builders)." "Even so," remarked Rabina, "a man should train himself to speak calmly without anger, as it is said (Ecc. 15, 10) And remove anger from thy heart."

R Samuel b. Nachmeni said in the name of R. Jonathan: "For a man who becomes excited, all kinds of Genhenna are assigned, as it is said (Ecc. 11, 10) And remove vexation from thy heart and cause evil to pass away from thy body. Evil, refers to the Gehenna, as it is said (Pr. 16, 4) Everything hath the Lord wrought for its destined end; Ye, even the wicked for the day of evil. Moreover even abdominal troubles will overtake him, as it is said (Deut. 28, 65) and the Lord will give thee, there a trembling heart, and a failing of eyes, and a faintness of soul. What is the thing that causes a failing of the eyes and the faintness of the soul? This refers to abdominal troubles." When he went to the land of Israel, Ulla was accompanied by two inhabitants of Chuzzai. While on the road, one arose and slaughtered (killed) his associate. He then said to Ulla: "Have I not done well?" Whereupon the latter replied: "Yes, indeed, go and uncover his throat" [that he may die sooner.] When he came before R. Jochanan he said: "Gor forbid I may have perhaps strengthened the hands of transgressors, [by not protesting his action."] Whereupon R. Jochanan answered him: "Why thou hast only saved thyself." R. Jochanan was then wondering: "Does not the passage. And the Lord will give thee, there a trembling heart, and a failing of eyes, and a faintness of soul, refer only to Babylon [and why did the above incident happen in the land of Israel?" Whereupon Ulla said to him: "At that time (Ib. b) we had not yet crossed the Jordan."