The Quran

وَالَّذينَ آمَنوا مِن بَعدُ وَهاجَروا وَجاهَدوا مَعَكُم فَأُولٰئِكَ مِنكُم ۚ وَأُولُو الأَرحامِ بَعضُهُم أَولىٰ بِبَعضٍ في كِتابِ اللَّهِ ۗ إِنَّ اللَّهَ بِكُلِّ شَيءٍ عَليمٌ

Muhammad Asad

And as for those who henceforth come to believe,¹ and who forsake the domain of evil and strive hard [in God's cause] together with you - these [too] shall belong to you;² and they who are [thus] closely related have the highest claim on one another in [accordance with] God's decree.³ Verily, God has full knowledge of everything.

Although the expression alladhina amanu (lit., "those who have come to believe") is in the past tense, the words min ba'd ("afterwards" or "henceforth") indicate a future time in relation to the time at which this verse was revealed: hence, the whole sentence beginning with alladhina amanu must be understood as referring to the future (Manor X, 134 f.; see also Razi's commentary on this verse).
I.e., they, too, shall belong to the brotherhood of Islam, in which the faith held in common supplies the decisive bond between believer and believer.
The classical commentators are of the opinion that this last clause refers to actual family relations, as distinct from the spiritual brotherhood based on a community of faith. According to these commentators, the above sentence abolished the custom which was prevalent among the early Muslims, whereby the ansar ("the helpers" - i.e., the newly-converted Muslims of Medina) concluded, individually, symbolic ties of brotherhood with the muhajirin ("the emigrants" from Mecca), who, almost without exception, arrived at Medina in a state of complete destitution: ties of brotherhood, that is, which entitled every muhajir to a share in the property of his "brother" from among the ansar, and, in the event of the tatter's death, to a share in the inheritance left by him. The above verse is said to have prohibited such arrangements by stipulating that only actual close relations should henceforth have a claim to inheritance. To my mind, however, this interpretation is not convincing. Although the expression ulu 'l-arham is derived from the noun rahm (also spelt rihm and rahim), which literally signifies "womb", one should not forget that it is tropically used in the sense of "kinship", "relationship" or "close relationship" in general (i.e., not merely blood-relationship). Thus, "in the classical language, ulu 'l-arham means any relations: and in law, any relations that have no portion [of the inheritances termed fara'id]" (Lane III, 1056, citing, among other authorities, the Taj al-'Arus). In the present instance, the reference to "close relations" comes at the end of a passage which centres on the injunction that the believers must be "the friends and protectors (awliya') of one another", and that all later believers shall, similarly, be regarded as members of the Islamic brotherhood. If the reference to "close relations" were meant to be taken in its literal sense and conceived as alluding to laws of inheritance, it would be quite out of tune with the rest of the passage, which stresses the bonds of faith among true believers, as well as the moral obligations arising from these bonds. In my opinion, therefore, the above verse has no bearing on laws of inheritance, but is meant to summarize, as it were, the lesson of the preceding verses: All true believers, of all times, form one single community in the deepest sense of this word; and all who are thus closely related in spirit have the highest claim on one another in accordance with God's decree that "all believers are brethren" (49:10).