Sins are from ignorance and a sinner is not a disbeliever unless he worships others along with Allah 'Azza wa Jall

Sahih al-Bukhari · Book 2 · Hadith 30

حَدَّثَنَا سُلَيْمَانُ بْنُ حَرْبٍ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ وَاصِلٍ الأَحْدَبِ، عَنِ الْمَعْرُورِ، قَالَ لَقِيتُ أَبَا ذَرٍّ بِالرَّبَذَةِ، وَعَلَيْهِ حُلَّةٌ، وَعَلَى غُلاَمِهِ حُلَّةٌ، فَسَأَلْتُهُ عَنْ ذَلِكَ، فَقَالَ إِنِّي سَابَبْتُ رَجُلاً، فَعَيَّرْتُهُ بِأُمِّهِ، فَقَالَ لِيَ النَّبِيُّ صلى الله عليه وسلم ‏"‏ يَا أَبَا ذَرٍّ أَعَيَّرْتَهُ بِأ…

Narrated Al-Ma'rur: At Ar-Rabadha I met Abu Dhar who was wearing a cloak, and his slave, too, was wearing a similar one. I asked about the reason for it. He replied, "I abused a person by calling his mother with bad…