Translation: His saying: “Claims to belong to someone other than his father while knowing it, except that he has disbelieved in Allah” appears here as “disbelieved in Allah,” but the phrase “in Allah” does not appear in the versions of Abu Dharr in Muslim or al-Isma‘ili.
The version without it is more correct. However, if the version with “in Allah” is authentically established, then it refers to someone who does this while believing it to be allowed, despite knowing it is forbidden. In the more common version, the intended meaning is disbelief in the blessing, not actual disbelief.
The apparent wording is not intended literally, rather it comes in the form of strong warning and rebuke. Or the meaning of disbelief here is that the one who does this has done something resembling the actions of the disbelievers. This issue has been explained in detail in Kitab Al Iman.
This hadith contains a clear ruling that it is forbidden to deny one’s known lineage or to claim belonging to someone other than one’s true father. The hadith includes the condition of knowing, which is necessary whether affirming or denying, because sin is only incurred by someone who does something knowingly and deliberately.
It also shows that it is permissible to use the term disbelief for sinful actions when the intention is to warn and rebuke.
Fath Al Bari By Ibn Hajar Asqalani (10/356-357)
