וַ֠יֹּאמֶר אַל־נָ֞א יִ֤חַר לַֽאדֹנָי֙ וַאֲדַבֵּ֔רָה אוּלַ֛י יִמָּצְא֥וּן שָׁ֖ם שְׁלֹשִׁ֑ים וַיֹּ֙אמֶר֙ לֹ֣א אֶֽעֱשֶׂ֔ה אִם־אֶמְצָ֥א שָׁ֖ם שְׁלֹשִֽׁים׃
Lalu ia berkata, “Janganlah kiranya Tuhan murka, izinkanlah aku berbicara lagi. Barangkali di sana hanya didapati tiga puluh orang.” Ia berfirman, “Aku tidak akan melakukannya, jika Aku mendapati tiga puluh orang di sana.”
Radak
ויאמר אל נא יחר, seeing that Avraham was afraid to belabour the same point of questioning G’d about how He administered justice, he now prefaced further questions with the request that G’d not become angry at him. In order not to stretch G’d’s patience, he now omitted reducing the numbers by five at a time, reducing them by ten each time, i.e. 40,30,20,10.
Sforno
לא אעשה, I will not do any harm at all to the three cities which are less guilty than Sodom.
Or HaChaim
ויאמר אל נא יחר לה׳ He said "Let my Lord not become angry." The reason that Abraham was concerned about G'd becoming angry this time was because he tried to add his own merit to make up the quorum of ten in one of the towns in case this was all that was lacking, whereas G'd would make up the quorum in the other towns. Abraham used the word נא again because he introduced a new element, i.e. use of his own merit as a protective factor. [The author may have deduced the principle that Abraham injected his own merit here because of the absence of the word אליו when he speaks to G'd. I believe the novelty of the author's approach is that he believed that throughout the dialogue reported by the Torah Abraham did not abandon the attempt to save all five cities. Ed.]