מדרש על רות 2:19

“Her mother-in-law said to her: Where did you glean today and where did you work? Blessed be he who acknowledged you. She told her mother-in-law with whom she had worked, and she said: The name of the man with whom I worked today is Boaz” (Ruth 2:19).
“Her mother-in-law said to her: Where did you glean today?” It is taught in the name of Rabbi Yehoshua: More than the owner does for the poor person, the poor person does for the owner, as Ruth said to Naomi: “The name of the man with whom I worked today is Boaz.” She did not say “who worked with me,” but rather “with whom I worked.” I performed many actions and many favors for him because he gave me one slice of bread.¹⁹⁶The mitzva of giving charity is more beneficial for the giver than the money is to the receiver. This is true not only in the World-to-Come but even in this world, as indicated by the word “today” in the verse (Etz Yosef). “[They will be punished for their iniquity] because [ya’an uvya’an] [they rejected my ordinances]” (Leviticus 26:43), yaan is ani.¹⁹⁷The punishment to which the verse refers will be administered due to mistreatment of the poor [ani – ayin, nun, yod] which is an anagram of yaan [yod, ayin, nun]. Rabbi Shilo of Naveh said: The destitute [haevyon], your wealth is dependent on him [honakh bei].¹⁹⁸Evyon is an acronym for yehav hon. If you do not support him, you will be forced to give away your wealth.
Rav Naḥman said: It is written: “[Give to him] because for [biglal] this matter [the Lord God will bless you]” (Deuteronomy 15:10) – there is a wheel [galgal] that spins over everyone in the world, like a water wheel;¹⁹⁹A wheel to which are attached buckets, which alternately fill with water and spill out their water. one that is full empties and one that is empty becomes filled.²⁰⁰Eventually the rich become poor and the poor become rich. Bar Kappara said: You do not have a person who does not experience this circumstance [poverty], and if not him, his son experiences it, and if not his son, his grandson experiences it. It was taught that Rabbi Eliezer ben Yaakov says: The vengeance against idolaters is in the hands of Israel, and the vengeance against Israel is in the hands of their poor. The vengeance against idolaters is in the hands of Israel, as it is stated: “I will place My vengeance upon Edom by means of My people Israel” (Ezekiel 25:14). The vengeance against Israel is in the hands of their poor, as it is stated: “He will cry to the Lord against you, and it will be a sin in you” (Deuteronomy 15:9). Rabbi Avun said: This poor person stands at your door and the Holy One blessed be He stands to his right. If you give to him, He who is standing to his right blesses you, and if not he will exact retribution from that man, as it is stated: “Because He will stand to the right of the indigent” (Psalms 109:31).
Rabbi Abbahu said: We must be grateful to the impostors among them. It was told that Rabbi Yoḥanan and Reish Lakish descended into the bathhouse of Tiberias and a poor person encountered them. He said to them: ‘Give me charity.’ They said to him: ‘When we exit we will give you charity.’ When they exited, they found that he was dead. They said: ‘Since we did not give him charity during his lifetime, we will tend to him in his death.’ When they rose to wash him, they found a purse of dinars with him. They said: ‘Rabbi Abbahu spoke well: We must be grateful to the impostors among them, as were it not for the impostors among them, when a person sees one of them asking him for charity and he does not give him immediately, he would be punished with death.’