Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 229
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 229, with English translation by Maimonides (Rambam).
להיות בית דין סוקלין באבנים, שנאמר: "וסקלתם אותם" (דברים כב,כד).
For a court to execute by stoning [the condemned] with stones, as [Deuteronomy 22:24] states: "And you shall stone them."