Midrash su Salmi 37:14

(R. Jochanan) said to him, I will (also) tell thee a parable. To what is the matter like? To this fountain which is bubbling and sending forth its water, and it is able to effect a discharge more powerful || than what it secretes; in like manner art thou able to speak words of the Torah in excess of what Moses received at Sinai. (R. Jochanan) continued: Lest thou shouldst feel ashamed on my account, behold I will arise and go away from thee. Rabban Jochanan ben Ẓakkai arose and went outside. (Thereupon) R. Eliezer sat down and expounded. His face shone like the light of the sun and his effulgence beamed forth like that of Moses, so that no one knew whether it was day or night. They went and said to Rabban Jochanan ben Ẓakkai: Come and see R. Eliezer sitting and expounding, his face shining like the light of the sun and his effulgence beaming like that of Moses, so that no one knows whether it be day or night. He came from (his place) behind him and kissed him on his head, saying to him: Happy are ye, Abraham, Isaac, and Jacob, because this one has come forth from your loins.

And it came to pass in the days of Amraphel (Gen. 14:1). R. Tanhuma the son of Abba opened the discussion with the verse The wicked began with the sword, and have bent their bow; to cast down the poor and the needy, to slay such as are upright in the way; their sword shall enter into their own heart, and their bows shall be broken (Ps. 37:14–15). The wicked began with the sword alludes to Cain, who slew his brother Abel before any other man was slain. Their sword shall enter into their own heart refers to the fact that Lamech later killed Cain. Another comment on The wicked began with the sword: This refers to Hanun the son of Nahash. Why? After the death of his father, David sent messages by the hand of his servants to comfort him (II Sam. 10:2), but Hanun seized David’s servants, shaved off half their beards and cut off their garments in the middle, even to their buttocks, and sent them away (ibid., v. 4). Hanun then dispatched emissaries to Aram-naharaim to hire thirty-two thousand charioteers in addition to the tens of thousands of troops he had in his army.¹¹II Sam. 10:16. They all assembled and encamped in one place. The Holy One, blessed be He, said to him: Wicked one, you began with the sword, hence the sword will penetrate your heart. Therefore, Joab and Abishai destroyed them all, as it is said: So Joab and the people that were with him drew nigh unto the battle to meet the Arameans; and they fled before them (ibid., v. 13).

[(Gen. 14:1:) NOW IT CAME TO PASS IN THE DAYS OF AMRAPHEL.] Thus did R. Tanhuma bar Abba begin: (Ps. 37:14-15:) THE WICKED HAVE DRAWN A SWORD … < TO BRING DOWN THE POOR AND NEEDY >…. THEIR SWORD SHALL ENTER THEIR HEART.²⁶Tanh., Gen. 3:7. What is the meaning of THE WICKED HAVE DRAWN (rt.: PTH) A SWORD? This refers to Cain, for until then no murderer had existed in the world. But Cain came and began (PTH) murder, as stated (in Gen. 4:8): CAIN AROSE [AGAINST HIS BROTHER ABEL AND MURDERED HIM]. The Holy One said to him: O wicked one, you have started using (rt.: PTH) the sword in the world. (Ps. 37:14:) THE WICKED HAVE DRAWN (rt.: PTH) A SWORD. This refers to Cain. (Ibid., cont.:) TO BRING DOWN THE POOR AND NEEDY, < TO SLAY THOSE WHO WAY IS UPRIGHT >. This refers to Abel. The Holy One said to him (i.e., Cain): You have let loose (rt.: PTH) a sword in the world. The sword shall enter the heart of that same person. (Ps. 37:15:) THEIR SWORD SHALL ENTER THEIR OWN HEART.