Midrasz do Samuela I 14:24

Furthermore, you may learn this as well from Saul the son of Kish, who said: Cursed be the man that eateth any food until it be evening, and I be avenged on my enemies (I Sam. 14:24). No one was to taste any food, but Jonathan heard not when his father charged the people with the oath; and he put forth the end of the rod that was in his hand, and dipped it into the honeycomb (ibid., v. 27). When Saul realized that the Philistines were overpowering the Israelites, he understood that someone had violated the oath. He examined the ephod and discovered that the stone of the tribe of Benjamin had grown dim. He cast lots between himself and his son Jonathan, and the lot indicated that Jonathan was responsible. He grasped his sword to slay him, as it is said: (Saul said:) “God do so and more also; thou shalt surely die, Jonathan.” And the people said unto Saul: “Shall Jonathan die, who hath wrought this great salvation in Israel?” (ibid., vv. 44–45).

(Exodus 18:3) "and her two sons … in a foreign land": R. Yehoshua says "foreign": as stated (i.e., literally). R. Elazar Homadai says: in a land of foreign (gods, i.e., idolatry). Moses said: Since the whole world serves idolatry, I will serve Him who spoke and brought the (whole) world into being. For when Moses said to Yithro, Give me your daughter Tzipporah as a wife, Yithro answered, If you do what I ask of you, I will give her to you as a wife. Moses: What do you ask? Yithro: Your first son must serve idolatry. Thenceforward, they may serve (G d) in heaven. Moses accepted. Yithro: Swear. And he swore, as it is written (Exodus 2:21) "Vayoel Moses, etc.", this being an expression for swearing, as in (I Samuel 14:24) "Vayoel Saul the people" (in context: "And Saul beswore the people.") And it is written (II Kings 5:3) "Hoel (in context: "Swear") and take two talents, etc." Therefore, the angel came forward to kill Moses (viz. Exodus 4:24), whereupon (Ibid. 25) "Tzipporah took a flint and cut off the foreskin of her son … (26) "And he (the angel) let go of him." R. Elazar b. Azaryah says: Repulsive is the foreskin, by which the wicked are demeaned, viz. (Jeremiah 9:25) "for all the nations are uncircumcised, and all the house of Israel is uncircumcised of heart." R. Yishmael says: Great is circumcision over which thirteen covenants was made. R. Yossi Haglili says: Great is circumcision, which overrides the Sabbath, which is liable to kareth (cutting-off). R. Yehoshua b. Karcha says: Great is circumcision, laxity in which did not permit all of Moses' merits to protect him for even a short time. R. Nechemiah says: Great is circumcision, which overrides (non-cutting of) plague-spots (viz. Devarim 24:8). Rebbi says: Great is circumcision, all of Moses' merits not standing for him in his duress. When the L rd told him "Take out My people, the children of Israel from the land of Egypt," because he was lax for a short time in (the) circumcision (of his son), the angel sought to kill him, viz. (Exodus 4:24) "and he was on the way in the lodging, etc." R. Yossi says: G d forbid that tzaddikim should be lax in circumcision for even a short while, but Moses expounded: Shall he circumcise (his son) and journey (to Egypt) — that would involve a risk of life (for the child.) Shall he wait and circumcise — the L rd has said to him: "Go and take My people Israel out of Egypt." But (his lapse was that) he preoccupied himself with his lodging before circumcising, wherefore the L rd sought to kill him, viz.: "And he was on the way in the lodging, etc." R. Shimon b. Gamliel says: The angel did not seek to kill Moses, but the child, viz. (Ibid. 25) "for you are a groom of blood to me." Who is called a "groom" (in this context), the child or Moses? The child.

(Devarim 1:5) "Across the Jordan, in the land of Moav, Moses ho'il (began) to explain": "hoalah" is "beginning," as in (Judges 19:6) "Begin ("hoel") now and stay overnight so that you will be refreshed," and (I Chronicles 17:27) "and now you have begun ("hoalta") to bless the house of your servant to be before You forever." And the sages say: "hoalah" is "swearing," as in (Shemoth 2:21) "And Moses swore ("vayoel") to remain with the man," and (I Samuel 14:24) "And Saul beswore ("vayoel") the people, saying 'Cursed be the man who will eat bread until the evening when I will be avenged of my enemies.'"