וַיֹּ֣אמֶר יְהוָ֔ה אִם־אֶמְצָ֥א בִסְדֹ֛ם חֲמִשִּׁ֥ים צַדִּיקִ֖ם בְּת֣וֹךְ הָעִ֑יר וְנָשָׂ֥אתִי לְכָל־הַמָּק֖וֹם בַּעֲבוּרָֽם׃
And the LORD said: ‘If I find in Sodom fifty righteous within the city, then I will forgive all the place for their sake.’
Read kabbalistic (mystical) interpretation of Genesis 18:26: and classical mystical sources.