Nedarim 50 - The vow of the satiated dog
Kalba Savua was a rich man, who got his name because everybody who entered his house hungry as a dog (Kalba) would leave it satisfied (Savua). His daughter Rachel saw Akiva, who was an unlearned shepherd forty years old, and made a deal with him: she will get engaged to him if Akiva promises her to go study Torah. Akiva promised, and they got engaged in secret. When Kalva Savua found out, he vowed against her getting any benefit from him and his possessions, and Rachel had to leave the house. They lived in poverty, and Akiva cried removing straw from her hair and promised to give her a gold diadem in the form of Jerusalem if he ever gets rich.
Once Elijah the prophet appeared as a poor man asking for straw to cover his wife who has just given birth. This was to console Akiva who could tell Rachel that they at least had straw.
Rachel convinced Akiva to go study to an academy, so he left the house and studied for twelve years. As he was coming back, he heard Rachel's neighbor saying to Rachel, "Your husband is not your equal, and moreover, he left you for twelve years - your father did right to disinherit you!" Rachel answered her, "If he would listen, I would want him to study another twelve years." On hearing this, now a Rabbi, Akiva went back for another twelve years. He came back as the leading scholar of the generation.
Eventually, Kalba Savua was able to annul his vow, because he would never make it, had he known that Akiva would become the scholar of such level. Rabbi Akiva became rich from Kalba Savua and because of the other five incidents. Here is the one.
A Roman by the name of Tinneius Rufus kept loosing arguments with Rabbi Akiva in front of the Roman Emperor. The wife of Tinneus, who was extremely beautiful, suggested this: if the husband gives her permission, she will go and seduce Rabbi Akiva. Since Jewish God hates promiscuity, Rabbi Akiva will loose God's favor, and Tinneus will win over him. She got the permission. When Rabbi Akiva saw her, he spat, laughed and cried. She asked, why? He said that he will tell her two reasons, but not the third one. He spat because beautiful as she was, she came from a putrid drop. He cried because even her exceeding beauty will one day rot in a grave. He did not tell her that he saw that in the future she will convert and marry him. She then became filled with remorse and asked him if she can repent her previous misdeeds. He answered, "yes." She converted and eventually married him, bringing him wealth.
Art: Peasant Woman Cutting Straw by Vincent Van Gogh