Is he sinning if he sees an evil action and does not denounce it?

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Check below answers in case you are looking for other related questions:
There is a lot of tabarruj in his country; should he denounce such women in the street?
Ruling on gathering to eat, offer condolences and recite Qur’aan together

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Does he have to denounce it every time he hears musical ring tones from his friends’ mobile phones?
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There is a lot of tabarruj in his country; should he denounce such women in the street?
Ruling on gathering to eat, offer condolences and recite Qur’aan together

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