Commentary for Berakhot 44:4
אמר רבא נהי דתקן עזרא טבילה נתינה מי תקן והאמר מר עזרא תקן טבילה לבעלי קריין אלא אמר רבא עזרא תקן טבילה לבריא המרגיל מ' סאה ואתו רבנן והתקינו לבריא לאונסו ט' קבין ואתו אמוראי וקא מיפלגי בחולה מר סבר חולה המרגיל כבריא המרגיל וחולה לאונסו כבריא לאונסו ומר סבר לבריא המרגיל מ' סאה וחולה המרגיל כבריא לאונסו ט' קבין אבל לחולה לאונסו פטור מכלום
Raba said : Granted that Ezra instituted immersion ; did he, then, institute the pouring of water? For lo, the teacher said, "Ezra instituted immersion for those who are Ba'al Keri" ! But, said Raba, Ezra instituted immersion in forty Saot for a healthy person whose emission was voluntary, and then the Rabbis came and instituted [the pouring of] nine Kabs for a healthy man when it was involuntary. After that the Amoraim came and differed as to what was to be done to a person in delicate health. Some were of opinion that the delicate person whose emission was voluntary was like a healthy man when it was voluntary [and required immersion], and a delicate person when it was involuntary like a healthy person when it was involuntary [and required pouring]. Others, however, were of opinion that the healthy person when it was voluntary required forty Saot ; and the delicate person when it was voluntary, like the healthy man when it was involuntary, required nine Kabs; but a delicate person whose emission was involuntary was exempt therefrom altogether.