Usury is of major sins, adultery is of major sins, oppressing the people, whosoever they are- whether they are your children and spouse or ordinary people are among the major sins, unjustly swearing is of major sins, false testimony is of major sins. Imam Sadiq (peace be upon him) says: The sins that Allah explicitly promises fire for them in the Holy Quran is a Major sin. As we read in a verse of the holy Quran that killing the innocent, polytheism and adultery is of major sins. After this verse Allah Almighty immediately says: " Their punishment will be doubled"(HUD , 20), the one who worships a false God before Allah Almighty, or the one who kills someone unjustly and in cold blood, or the one who commits adultery must know that they will be afflicted to a severe punishment on the day of resurrection. This is a conception of people who thinks that the major sins are some practical sins; namely, the sins they commit by means of tongue, hands, stomach or carnal desires.
source : erfan.ir
