Midrash su Salmi 78:51

“Both of them died, Maḥlon and Kilyon, and the woman was bereft of her two children and of her husband” (Ruth 1:5).
“Both of them died, Maḥlon and Kilyon.” Rabbi Ḥunya, Rabbi Yehoshua ben Rabbi Avin, and Rabbi Zavda, son-in-law of Rabbi Levi [said]: The all-Merciful [God] never exacts retribution against a person himself initially. From whom do you learn this? From Job, as it is stated: “There came a messenger to Job, and said: ‘The oxen were plowing [and the donkeys grazing beside them; and Sheba fell upon them, and took them; they smote the servants by sword; and only I by myself escaped to tell you]’” (Job 1:14–15).⁹⁰God did not initially kill Job or even afflict him with bodily pain; He struck Job’s property. Rabbi Ḥama ben Rabbi Ḥanina said: The Holy One blessed be He showed him a representative taste of the World to Come, “the plowman will meet the reaper” (Amos 9:13).⁹¹Donkeys do not typically graze in fields where oxen have just plowed. This was Job’s taste of the World to Come, when produce will be ready to be reaped as the field is still being plowed.
“Sheba fell upon them [and took them and smote the lads by sword].” Rabbi Abba bar Kahana said: They emerged from the village of Kerinos⁹²In Media. and went on all the rural paths until Migdal Tzabba’im⁹³In the Land of Israel. and they died there.⁹⁴At first they were attacked and taken captive along with the herd. Only later were they killed. “And only [rak] I by myself [levadi] escaped.” Rabbi Ḥanina said: [The term] Rak is restrictive; he, too, was broken and stricken. Rabbi Yudan said: Levadi.⁹⁵In the sense of bedding, meaning that the messenger was bedridden. The word leved means felt, which can be used for bedding. “This one was still speaking” (Job 1:16); he, too, once he stated his tidings, he died.
“This one was still speaking and that one came and said: The Chaldeans deployed in three columns…” (Job 1:17). Rabbi Shmuel bar Naḥman said: When Job heard, he began mobilizing his armies for war. He said: ‘How many armies can I enlist, how many troops can I muster? This is the most despicable nation in the world: “Behold, the land of the Chaldeans, this is a people that is not” (Isaiah 23:13). If only it had not been.⁹⁶If only the Chaldeans had never come into existence. It comes to intimidate me?’ But once [the messenger] said to him: “The fire of God fell from the heavens” (Job 1:16), [Job] said: ‘It is from the heavens; what can I do?’ – “I was silent and I did not go out the door” (Job 31:34).
Immediately, “he took an earthenware shard to scratch himself” (Job 2:8).⁹⁷This was after he was afflicted with boils. His body was afflicted only after his property was damaged. So it was in Egypt, as well: “He struck their vines and their fig trees” (Psalms 105:33). Then, “He subjected their livestock to the hail” (Psalms 78:48). And then, “He smote every firstborn in Egypt” (Psalms 78:51). Regarding leprosy, too, the same is true: Initially it afflicts his house. If he repents, excellent; if not, they require removal, as it is stated: “The priest shall command and they will remove [the stones]” (Leviticus 14:40). If he repents, excellent; if not, they require demolition. If he repents, excellent; if not, [the signs of leprosy] come upon his garments and they require laundering. If he repents, excellent; if not, they require rending, as it is stated: “He shall rip it from the garment” (Leviticus 13:56). If he repents, excellent; if not they require burning, as it is stated: “He shall burn the garment” (Leviticus 13:52). Then [leprosy] comes upon his body. If he repents, excellent; if not, he goes and comes.⁹⁸He leaves the camp for seven days and then returns. If he repents, excellent; if not, “he shall dwell in isolation, his dwelling shall be outside the camp” (Leviticus 13:46). Regarding Maḥlon and Kilyon, too, the same is true. Initially, it was their horses, their donkeys, and their camels. Then “Elimelekh died.” Then, “both of them died, Maḥlon and Kilyon.”
“And the woman remained bereft,” Rabbi Ḥanina said: She became the remnants of the remnants [of meal offerings].⁹⁹When her husband died, she was like the remnant; now that her sons died, she was like the remnant of the remnant.

And it came to pass in the middle of the night, that the Lord smote all the firstborn in the land of Egypt (Exod. 12:29). The Creator of the night divided the night precisely. The Lord smote all the first born. It was the Lord Himself who smote the firstborn and not His emissary (Moses). In fact, even though a man was elsewhere, and his firstborn was in Egypt, he died. How do we know that the firstborn of the Cuthites, Puthites, and Ludites were also slain? It is said: And smote all the firstborn in Egypt, the first fruits of their strength in the tents of Ham (Ps. 78:51).⁸Ham was the ancestor of Cush, Put, and Lud (Gen. 10:15). Only the firstborn of the Pharaoh remained alive in fulfillment of the verse However, it was for this that I raised you up (Exod. 9:16). And Ba’al Saphon was the only idol remaining, to mislead them, in fulfillment of the verse He increaseth the nations, and destroyeth them (Job 12:23). Unto the firstborn of the captives (Exod. 12:29). Why were the firstborn of the captives punished? Because they had rejoiced in the decrees promulgated against Israel. Hence it is written: He that is glad at calamity shall not be unpunished (Prov. 17:5). You must not be of the opinion that only the captives reacted in that manner, for the slaves and handmaidens did likewise, as is said: Even unto the firstborn of the maidservants that is behind the mill (Exod. 11:5); that is, even those who were legally bound to the millers. Even their firstborn cattle were destroyed lest the people assert: “Our deities are powerful, and that is why punishment was imposed upon them (and not upon us).”

"and I shall smite": I might think, through an angel or through a messenger; it is, therefore, written (Ibid. 29) "and the L rd (Himself) smote every first-born" — not through an angel or a messenger. "and I smote every first born": even from different places. Whence do I derive (the same) even for the first-born of Egypt who were in other places? (From Psalms 136:10) "He smote Egypt through their first-born" (connoting, even if they were not in Egypt). Whence do I derive (the same for) the first-born of Cham and Cush? (viz. Genesis 10:6) From (Psalms 78:51) "And He struck every first-born in Egypt, the first fruit of their strength in the tents of Cham." "from man until beast": The initiator of the transgression was struck first. Similarly, (Genesis 7:23) "And all that existed on the face of the earth was blotted out — from man to beast, etc." Similarly, (Exodus 14:4) "And I will be honored through (the downfall of) Pharaoh and his entire host." Similarly, (Devarim 13:16) "Smite the inhabitants of that city … and its cattle." Similarly, (Numbers 5:27) "and her belly ('first in the transgression') will swell, and her thigh will fall." Here, too, "And I shall smite every first-born in the land of Egypt from man until beast." The initiator of the transgression was struck first. Now does this not follow a fortiori, viz.: If in His measure of punishment — the lesser (measure) — the initiator of the transgression is smitten first, how much more so in His measure of beneficence — the greater (measure) — (is the initiator of the mitzvah rewarded first)!

Another explanation: "And it was in the middle of the night" - this is [the meaning of] that which is written (Proverbs 31:18), "She has understanding as her merchandise is good, her candle does not, etc." You find that the verse stated (Exodus 12:30), "as there was not a house that did not have a dead person there." How? If you count each and every drop that an Egyptian put out to each and every woman [that had not yet given birth] or the first drop [to women that had already given birth from other men], it will be found that all of the boys were dying, as it is stated (Psalms 88:51), "And he smote every firstborn in Egypt, the beginning of their strength in the tents of Cham." The first drop [that were] female firstborns also died, except for Batya the daughter of Pharaoh who had a good (tov) defender; that was Moshe, as it is stated (Exodus 2:2), "and she saw that he was goodly (tov)." Hence Shlomo said "She has understanding as her merchandise is good." "And she gets up while it is still night" (Proverbs 31:15) - in what night? "And it was in the middle of the night."

Many miracles did the Holy One, blessed be He, do for Israel: He killed the firstborn of Egypt - that were compared to animals, as it is stated (Ezekiel 23: 20), "that their flesh is the flesh of donkeys;" He killed the firstborn of the captives; since they said to the captive that was imprisoned in the jail, "Do you want to go out and the Jews will [also] be delivered?" And he would say, "We will not ever leave from here in order that Israel not go out." That is why He judged them with [the Egyptians] - "from the firstborn of Pharaoh... to the firstborn of the captive." (Exodus 12:29) There is a parable about a king who made a joyous occasion for his son and killed his enemies. The king said, "Anyone who caused me joy should come to my son's joyous occasion, and anyone who is hated by me will be killed with the enemies." So [too], God made a joyous occasion for Israel, since He redeemed them - God said, "Anyone who loves My son should come and rejoice with My son." The proper ones of Egypt came and made a Pesach sacrifice with the Jews and went out with them, as it is stated (Exodus 12:38), "And also a mixed multitude went out with them." And all those that wanted Israel not to be redeemed died with the firstborn, as it is stated (Pslams 78:51), "And He smote all the firstborn of Egypt." They all cried out, as it is stated (Exodus 12:39), "and there was a great outcry in Egypt." They all came to kill Pharaoh. At that time, "And the Egyptians pressed upon the people (here read, as about the people)." (Exodus 12:33) And [the Jews at that time] were reciting Hallel; and Pharaoh announced to his warriors, "Come, let us call to Moshe and Aharon." God said to him, "You are releasing my children at night? You will not release my children at night, but rather they will go out [in plain sight,] in the middle of the day." The Jews dispersed into all of Egypt at that time, as it is stated (Ibid. 35), "And the children of Israel did according to the word of Moshe and borrowed from Egypt." And Moshe was busy with the bones of Yosef and the vessels of the Tabernacle that were prepared by Yakov, our father. And hence David said (Pslams 58:11), "The righteous one will rejoice, since he saw vengeance."