Someone once asked Imam Sadiq (as): what is the criterion for knowing the great sins?
Imam Sadiq (as) stated: whatever sin which is promised Hellfire in the Holy Quran is considered great sin
source : erfan.ir
Someone once asked Imam Sadiq (as): what is the criterion for knowing the great sins?
Imam Sadiq (as) stated: whatever sin which is promised Hellfire in the Holy Quran is considered great sin