"It is those who believe (in the Oneness of Allah and worship none but Him Alone) and confuse not their belief with Zuim (wrong i.e., by worshipping others besides Allah).. ." (V.6:82) Sahih al-Bukhari 4629
Arabic hadith text
حَدَّثَنِي مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا ابْنُ أَبِي عَدِيٍّ، عَنْ شُعْبَةَ، عَنْ سُلَيْمَانَ، عَنْ إِبْرَاهِيمَ، عَنْ عَلْقَمَةَ، عَنْ عَبْدِ اللَّهِ ـ رضى الله عنه ـ قَالَ لَمَّانَزَلَتْ {وَلَمْ يَلْبِسُوا إِيمَانَهُمْ بِظُلْمٍ} قَالَ أَصْحَابُهُ وَأَيُّنَا لَمْ يَظْلِمْ فَنَزَلَتْ {إِنَّ الشِّرْكَ لَظُلْمٌ عَظِيمٌ}
Translation
Narrated `Abdullah
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)