«إِنَّ بَعْضَ الظَّنِّ إِثْمٌ»
Indeed, some suspicion is sinful.
The stranger recites this short Qurʾānic statement (49:12) in response to the audience's doubts. Its force in the scene is that a surprising claim does not justify inventing blame on the basis of appearance alone.
Baʿḍ (“some”) matters: the sentence does not declare every suspicion sinful. In this literary setting, reasonable questioning must be distinguished from a baseless accusation. The quotation challenges the audience's manner of judgement without automatically proving the stranger's claim.