In the name of Allah, the Most Merciful, the Most Compassionate.
May Allah bless our master Muhammad, his family, and grant them peace.

Book of Prescribed Punishments (Hudud)

Chapter: Matters that obligate flogging or stoning of the fornicator—whether because of previous marital status (ihsan) or for other reasons

No corporal hadd or bodily obligation is due except against one who has reached puberty. We explained the signs of puberty at the beginning of the Book of Fasting and mentioned the divergences among Mālik’s companions on the issue. An insane person who never regains sanity is subject to neither hadd nor religious obligation.

Stoning (rajm) is imposed only on one who is muḥṣan—that is, previously married—when the conviction is established either by his own confession to fornication (zina) and his persistence without retracting it, or by decisive testimony from four upright witnesses who attest that they saw the act of penetration, the minimum of which is the meeting of the two circumcised parts.

The ihsan that entails stoning requires that the adulterer be free, adult, sane, and that he has previously had sexual intercourse with a spouse in a sound marriage that both parties acknowledge.