ONE WHO WAS STRINGENT NOT TO LET NOCHRIM EXTINGUISH
Why does it say 'a case occurred, and a fire erupted...'?
Iyun Yakov: It was not common for fires to erupt, for it is common only where there is Chilul Shabbos, and Yosef was very careful about Kevod Shabbos! Therefore, even when a fire erupted for a reason, it extinguished by itself.
What is the meaning of 'he did not allow them, due to the honor of Shabbos'?
Maharsha: It does not say due to the Isur of Shabbos, for he knew that there is no Isur, like we conclude. Rather, he was stringent due to the honor of Shabbos, lest people suspect that he asked them to extinguish.
Daf Al ha'Daf: Yad David said, why did Chachamim need to tell Yosef that he did not need to be stringent? It seems that he erred; they informed him that he could have let them extinguish. However, 'due to the honor of Shabbos' implies that he knew that there is no Isur! Sefas Emes said, the Heter to let Nochrim extinguish is due to loss. Since he would not have lost (it was the king's money), there was no Heter; he needed to be stringent. Therefore, he merited this reward (rain extinguished the fire).
ONE WHO WAS SPARED BECAUSE HE KNEW THE HALACHAH
Was this episode on Shabbos?
Rashi: Yes.
Ha'Boneh: Can it be that the people brought Aba in front of the Reish Galusa on Shabbos, to force him to pay?! Perhaps on other occasions they pained him in front of the Reish Galusa, and once, on Shabbos, Aba mentioned that one may trample spit l'Fi Tumo. The Reish Galusa told the people not to claim from him after this. I prefer to say that indeed, they pressed him to pay on Shabbos. We find that people of the Reish Galusa's house were wayward, e.g. Gitin 67b and Berachos 28a. (NOTE: Why does he cite Berachos 28a? There it discusses R. Gamliel's servants! Does he learn from a Kal v'Chomer that the Reish Galusa's household were wayward?! - PF)
Rav Elyashiv: They pressed him to pay on Erev Shabbos, and he was still there on Shabbos when the spit was around. If the spit bothered them, it is like Graf Shel Re'i (a Kli for excrement - one may remove it)! Rather, the Reish Galusa was merely concerned lest one transgress trampling it. Was he concerned for this, but not for acting like a creditor?! One may press for payment if he is unsure if the borrower can pay. Or, perhaps Aba owed not due to a loan, so "Lo Sihyeh k'Nosheh" did not apply.
Why did the Reish Galusa command to leave him alone?
Ha'Boneh: Chochmah saves a Chacham from misfortune. When the Reish Galusa heard that Aba engages in Halachos and knows them fluently, he commanded to cease being like a [harsh] creditor to pain him.