Sahih Bukhari Volume 1, Book 2, Hadith 32

حَدَّثَنَا أَبُو الْوَلِيدِ، قَالَ حَدَّثَنَا شُعْبَةُ، ح‏.‏ قَالَ وَحَدَّثَنِي بِشْرٌ، قَالَ حَدَّثَنَا مُحَمَّدٌ، عَنْ شُعْبَةَ، عَنْ سُلَيْمَانَ، عَنْ إِبْرَاهِيمَ، عَنْ عَلْقَمَةَ، عَنْ عَبْدِ اللَّهِ، قَالَ لَمَّا نَزَلَتِ ‏{‏الَّذِينَ آمَنُوا وَلَمْ يَلْبِسُوا إِيمَانَهُمْ بِظُلْمٍ‏}‏ قَالَ أَصْحَابُ رَسُولِ اللَّهِ صلى الله عليه وسلم أَيُّنَا لَمْ يَظْلِمْ فَأَنْزَلَ اللَّهُ ‏{‏إِنَّ الشِّرْكَ لَظُلْمٌ عَظِيمٌ‏}

Narrated By 'Abdullah : When the following Verse was revealed: "It is those who believe and confuse not their belief with wrong (worshipping others besides Allah.)" (6:83), the companions of Allah's Apostle asked, "Who is amongst us who had not done injustice (wrong)?" Allah revealed: "No doubt, joining others in worship with Allah is a great injustice (wrong) indeed." (31.13)