Or HaChaim on Genesis 18:31/אור החיים על בראשית י״ח:ל״א

1 ויאמר הנה נא הואלתי לדבר. He said: "Here I have already dared to speak." Abraham pleads here that G'd's merit should protect twenty of the thirty righteous men whereas his own merit should suffice to protect the people in a third location by complementing the quorum of ten. Seeing that Abraham did not introduce a new element this time, he did not worry about G'd becoming angry at his being presumptuous. The emphasis on אל ה was to underline that he did not try to expand what he considered his own merit. [I believe that in order to understand the author one must assume that the twenty mentioned in the verse do not need additional protection. All that Abraham worried about was the three towns which did not have ten good people each to protect them. Ed.]