´It was narrated from 'Aishah that:` The Messenger of Allah [SAW] said: "It is not permissible to shed the blood of a Muslim except in three cases: An adulterer who had been married, who should be stoned to death; a man who killed another man intentionally, who should be killed; and a man who left Islam and waged war against Allah, the Might and Sublime, and His Messenger, who should be killed, or crucified, or banished from the land."
Brief Explanation
1؎: The portion of «من الإسلام» is not present in Sunan Abi Dawud; on this basis, Imam Khattabi has considered the referent of this hadith to be Muslim combatants (warriors) and rebels, whose punishments have already been discussed in the footnote to hadith number 4029. Among the three punishments (the statement about giving the ruler the choice pertains to disbelieving combatants).
2؎: Thus, regarding the combatants against Islam, there is an option that the ruler may kill them, crucify them, or exile them.
Explanation & Benefits
Hafiz Muhammad Ameen
(1) The relevance of the hadith to the chapter is absolutely clear.
(2) It is understood that, in the case of bandits, rebels, and apostates, the ruler has the authority to choose any one of the aforementioned punishments; that is, he may increase or decrease the punishment according to the nature of the crime. And Allah knows best.
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 4053
Hafiz Muhammad Ameen
If a slave commits adultery, even if he is married, he will not be subjected to stoning (rajm), because for him the prescribed punishment (hadd) is half. And that is fifty lashes; stoning cannot be halved.
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 4022
Hafiz Muhammad Ameen
The author's (rahimahullah) argument is based on the apparent wording, that it is not permissible to kill any Muslim except for these three crimes. And among them, the second crime is the killing of a Muslim, not a disbeliever (kafir). This argument is also supported by the forthcoming ahadith, in which it is explicitly stated that a Muslim will not be killed in retaliation for a disbeliever. As for "al-nafs bil-nafs" (a life for a life), this is not general, because no one holds the opinion that a Muslim may be killed in retaliation for a harbi disbeliever (a disbeliever at war with Muslims). Just as the harbi disbeliever is excluded, in the same way, based on these ahadith, the dhimmi disbeliever (a non-Muslim under Muslim protection) is also excluded. (For further details, see: Fawaid wa Masail Hadith: 4738)
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 4747