When:"...and confuse not their belief with wrong." (6.82) was revealed, the Prophet's companions said, "Which of us has not done wrong?" Then there was revealed:-- "Verily joining others in worship with Allah is a tremendous wrong indeed." (31.13)
لَمَّا نَزَلَتْ {وَلَمْ يَلْبِسُوا إِيمَانَهُمْ بِظُلْمٍ} قَالَ أَصْحَابُهُ وَأَيُّنَا لَمْ يَظْلِمْ فَنَزَلَتْ {إِنَّ الشِّرْكَ لَظُلْمٌ عَظِيمٌ}