Nasai

(1) In this hadith, the mention is of killing (qatl), not fighting (qital). By "killing" is meant execution as a legal punishment (hadd), and it is only permissible in these three principles. However, fighting (qital), that is, combat, can also be waged against rebels and those who refuse to pay zakat, etc.

(2) "Becomes a disbeliever"—that is, after accepting Islam, if one becomes an apostate (murtad), then he will be executed as a legal punishment (hadd). However, if he repents before the punishment is carried out, he will be pardoned.

(3) "Leaves the community"—this does not mean that if, after becoming an apostate, he remains among the Muslims, then the legal punishment (hadd) will not be applied to him, because this is actually an explanation of apostasy (irtidad), i.e., becoming an apostate is to separate oneself from the community of Muslims. According to the Hanafi scholars, a female apostate is not to be executed but rather imprisoned; however, this is contrary to explicit narrations.

(4) The killer, whether a free man or a slave, male or female, will be executed in retribution (qisas). However, there is a difference of opinion regarding executing a free man in place of a slave, the details of which can be seen in the benefits of hadith: 4838.

(5) "A similar narration"—Ibrahim al-Nakha'i had this narration from Aisha radi Allahu anha, while A'mash had it from Abdullah ibn Mas'ud radi Allahu anhu. When A'mash narrated Abdullah ibn Mas'ud's narration to Ibrahim al-Nakha'i, Ibrahim narrated to him this narration from Aisha radi Allahu anha. Thus, both benefited from each other.