It may then be said that the relative pronoun may follow the same pattern, as in His words:

“And the two among you who commit it”

If it is established that, in the dialect of Quraysh, they say ra’aytu alladhayni faʿalā (“I saw the two who did it”) and marartu bi-alladhayni faʿalā (“I passed by the two who did it”)—but if not, it may be said that this pronoun retains the alif in all three cases, because it is indeclinable, and its alif takes the place of the yā’ in alladhīna (“those who”). What al-Farrā’, Ibn Kaysān, and others have stated supports this. Al-Farrā’ compared the demonstrative form to alladhīna, and comparing alladhāni (“the two who”) to it is even more appropriate. Ibn Kaysān explained that a noun of indeterminate reference is indeclinable and does not display case inflection; he therefore treated its dual like its singular and plural. This analysis also applies to the relative pronoun.

This is further supported by the fact that personal pronouns belong to the same category. Nominative and accusative pronouns have both attached and independent forms, whereas genitive pronouns have only attached forms. This is because the genitive is governed only by a preposition or a noun to which it is annexed; it cannot precede its governing word and therefore cannot be detached from it.

The attached singular pronoun is the kāf in akramtuka (“I honored you”) and marartu bika (“I passed by you”). In the plural, one says akramtukum (“I honored you all”) and marartu bikum (“I passed by you all”). In the dual, an alif is added in both the accusative and the genitive: akramtukumā (“I honored you two”) and marartu bikumā (“I passed by you two”). The same applies to the nominative: in the singular and plural, one says faʿalta (“you did”) and faʿaltum (“you all did”), and in the dual, faʿaltumā (“you two did”). The alif alone is added to mark the dual in the nominative, accusative, and genitive, just as it is added to the independent pronouns iyyākumā (“you two”) and antumā (“you two”).

All of this demonstrates that the dual of indeclinable nouns has a single form in all three cases: they made no distinction between its nominative form and its accusative and genitive forms