Surah Al-Nisâ’ 4:31

إِن تَجْتَنِبُوا كَبَائِرَ مَا تُنْهَوْنَ عَنْهُ نُكَفِّرْ عَنكُمْ سَيِّئَاتِكُمْ وَنُدْخِلْكُم مُّدْخَلًا كَرِيمًا

4:31 This verse deals with the subject of ethics. One evil deed leads to committing another, until the evil deeds reach a point at which they become significant. For example, entertaining the idea or actually considering committing a theft is already a sin; and setting out with the intent to do it is yet another, until the theft itself is committed.

There is no distinct classification of a major sin and a minor sin in the Qur’ân. The lists of grievous sins as given in some Books of Hadîth do not encompass all sins, nor did the compilers of such books ever mean to do so. They serve the purpose of mentioning specific sins with reference to certain environmental circumstances and particular situations. Ibn Qayyam, who occupies an exalted position among the Muslim scholars, has discussed the topic at length in his book Madârij al-Sâlihîn. In short, the major sins are the infringements of the prohibitions laid down in the Holy Qur’ân by Allâh, and the minor sins are the evil deeds leading to the last stage (infringement) of a prohibition. This verse is interpreted as saying that if a person restrains himself from committing the final evil deed, he will be forgiven for all the preliminaries. It also conveys the idea that if we avoid doing things, the renunciation of which seems hard to us, we will eventually be able to rid ourselves of evil inclinations and ideas. The expression mud´khal مُّدْخَلdenotes “place and manner of entering” (Râzî).