ישׁב yshb "sit, be enthroned or live". In Amos the participle is used at: 1:5, 8; 3:12; 8:8; 9:5 with the sense of "inhabitants" or I believe in the singular of "the person enthroned" = "ruler" 1:5, 8. The verb is used as a verb only at 5:11 and 9:14.