창세기 18:29의 주석

. אולי ימצאון שם ארבעים PERADVENTURE THERE SHALL BE FORTY FOUND THERE — then let four cities be saved; so, too, let thirty save three of them and twenty save two of them or ten save one of them.

ויוסף עוד לדבר אליו. Abraham continued to speak to Him (G'd). This is a continuation of the prayer that G'd Himself should act as the one making up the requisite quorum. The expression ויוסף…אליו means that Abraham continued in the same vein adding that G'd's making up the quorum would apply even if not all the towns would could be saved by that method.

ויוסף עוד..לא אעשה, I will not utterly destroy the whole region, as G’d had already said in verse 28 when He worded this as לא אשחית. Basically, the same considerations prevail in respect of all these numbers, G’d varying His reply by sometimes phrasing it as לא אשחית and other times as לא אעשה, “I will not do.”