Ketubot 50A

ועשיתינהו (לזניה) [וזנוה]. אי אמרת בשלמא לאו דינא, משום הכי עשיינהו. אלא אי אמרת דינא ⁠— עשיינהו בעי?

and I forced them to feed him, for which he is grateful. The Talmud interprets this incident in light of the issue at hand: Granted, if you say that this was not according to the halakha, i.e., the man’s sons had the right to refrain from sustaining him, due to that reason R' Yonatan had to force them to feed their father; but if you say this is the halakha, i.e., the man’s sons were required to sustain him, why did he need to force them to provide the sustenance of their own accord? The court could have simply requisitioned the necessary amount from the property. This shows that the halakha is not in accordance with the opinion of R' Ile’a.

אמר רבי אילעא, באושא התקינו: המבזבז ⁠— אל יבזבז יותר מחומש. תניא נמי הכי: המבזבז ⁠— אל יבזבז יותר מחומש, שמא יצטרך לבריות. ומעשה באחד שבקש לבזבז [יותר מחומש], ולא הניח לו חבירו. ומנו ⁠— רבי ישבב. ואמרי לה: רבי ישבב, ולא הניחו חבירו, ומנו ⁠— רבי עקיבא.

§ Apropos the ordinances instituted by the rabbis in Usha, the Talmud cites another one. R' Ile’a said: In Usha the rabbis instituted that one who dispenses his money to charity should not dispense more than 1/5th. That opinion is also taught in a baraita: One who scatters should not scatter more than 1/5th, lest he render himself destitute and need the help of other people. And an incident occurred involving a certain individual who sought to dispense more than 1/5th of his property as charity, and his friend did not let him act upon his wishes. And who was this friend? R' Yeshevav. And some say that R' Yeshevav was the one who wanted to give too much charity, and his friend did not let him do so, and who was the friend? R' Akiva.