וַיִּקְח֨וּ אֶת־ל֧וֹט וְאֶת־רְכֻשׁ֛וֹ בֶּן־אֲחִ֥י אַבְרָ֖ם וַיֵּלֵ֑כוּ וְה֥וּא יֹשֵׁ֖ב בִּסְדֹֽם׃
און זײ האָבן צוגענומען לוט, דעם זון פֿון אבֿרמס ברודער, װאָס איז געזעסן אין סדום, און זײַן פֿאַרמעג, און זײַנען אַװעקגעגאַנגען.
Rashi
והוא ישב בסדם FOR HE DWELT IN SODOM — What made this happen to him? The fact that he was dwelling in Sodom (Genesis Rabbah 42:7).
Chizkuni
והוא יושב בסדום, “and he dwelled in Sodom;” note the singular mode; none of his relatives lived in Sodom. This accounted for his being taken captive alone. Alternate explanation: he entered the city now that he was afraid of being solitary against the warring nations.
Sforno
ויקחו את לוט בן אחי אברם, they made a special effort to capture Lot because he was Avram’s nephew. They were aware of his wealth. They were expecting that Avram would pay a heavy ransom for the release of his nephew.