What is the nature of adultery that necessitates the prescribed punishment (Hadd), involving full penetration, and what is the ruling on external contacts that are not followed by penetration?

The fornication that necessitates the prescribed punishment (حدّ) is the insertion of the glans into the vagina. Its ruling for the virgin is one hundred lashes and one year of exile, and for the married person (thayyib) it is stoning until death. As for insertion into the anus, that is sodomy.

Fornication also includes what is less than that, such as touching, embracing, kissing, and unlawful looking. The perpetrator of such acts is gravely sinful if he does not repent and seek Allah's forgiveness. This is based on the Prophet's (peace be upon him) saying: "The son of Adam has been allotted his share of zina (fornication/adultery), which he will inevitably attain. The zina of the eyes is looking, the zina of the ears is listening, the zina of the tongue is speaking, the zina of the hand is touching, the zina of the foot is walking [towards it], and the heart yearns and wishes, and the private part confirms or denies that."

Whoever falls into any of these acts must hasten to sincere repentance, frequently seek forgiveness, perform good deeds, and avoid every cause that leads to them.