340.Verily, Allah sent Muhammad (peace and blessings of Allah be upon him) with truth and He sent down the Book upon him and the verse of stoning was included in what was sent down to him. We recited it, retained in our memory and understood it. Allah's Messenger (peace and blessings of Allah be upon him) awarded the punishment of stoning to death (to the married adulterer and adulteress) and after him, we also awarded the punishment of stoning to death. I am afraid that, with the lapse of time, the people (may forget it) and may say: We do not find the punishment of stoning to death in the Book of Allah, and thus go astray by abandoning this duty prescribed by Allah. Stoning to death is a duty laid down in Allah's Book for married men and women who commit adultery when proof is established.
(Muslim).
(The Penal Law of Islam by Muhammad Iqbal Siddiqi).