How is the fornicator stoned, when verse 25 of Surah An-Nisa confirms flogging for the chaste, in His saying, the Almighty: "But if, when they are safely married, they commit indecency, then on them is half the punishment for free, chaste women" [Qur'an 4:25], and stoning cannot be halved?

The Almighty's saying: "And if they commit indecency upon marriage, then for them is half of what is due to free married women of punishment" (Quran 4:25) is specific to female slaves. Male slaves are included with them, so their punishment is fifty lashes, whether they are virgins or previously married. As for the free, married fornicator, his or her حكم (ruling) is stoning to death, whether male or female. This is established by the Qur'an, the Sunnah, and scholarly consensus. The verse of stoning was revealed, then its recitation was abrogated while its ruling remained.