Narrated `Abdullah: When the Verse:-- 'Those who believe and mix not their belief with wrong.' was revealed, the Muslims felt it very hard on them and said, O Allah's Apostle! Who amongst us does not do wrong to himself? He replied, The Verse does not mean this. But that (wrong) means to associate others in worship to Allah: Don't you listen to what Luqman said to his son when he was advising him, O my son! Join not others in worship with Allah. Verily joining others in worship with Allah is a great wrong indeed. (31.13)