ייִדישער מחשבֿה אויף רות 2:14

Rabbi Yitzchak bar Marion said: The Torah teaches you proper conduct—that when a person performs a mitzvah, they should do it with a joyful heart. For if Reuben had known that the Holy One would write about him, "And Reuben heard and saved him from their hands" (Genesis 37:21), he would have carried [Joseph] on his shoulders and brought him to his father. If Aaron had known that the Holy One would write about him, "And behold, he is coming out to meet you, and when he sees you he will rejoice in his heart" (Exodus 4:14), he would have gone out to meet him with drums and dances. If Boaz had known that the Holy One would write about him, "And he gave her roasted grain" (Ruth 2:14), he would have brought fattened calves and fed her. (Vayikra Rabbah [Margaliot], 34:8, p. 790)