Tafsir of Sad 38:46

"Indeed, We have chosen them for a pure quality..." is a justification for what they have been described with. The ba (in bi-khalisatin) is for causality. Khalisatin is an active participle, and its nunation is for glorification.

His saying, "the remembrance of the [true] Abode," is an explanation of it after it was made ambiguous, to further glorify it. It is also permissible that it be a predicate for an implied pronoun, meaning: "It is the remembrance of the [true] Abode." Regardless of which it is, dhikra (remembrance) is an infinitive annexed to its object. The definite article in "the Abode" (al-dar) is for specification, meaning the Hereafter. In this, there is an indication that it is the true Abode, while this world is merely a metaphor. This means: We have made them pure for Us by means of a pure, sublime quality that is free of any admixture—namely, their constant remembrance of the Hereafter. For their purity in obedience is due to their remembrance of it; their focus and the object of their contemplation in everything they do or leave undone is the proximity of Allah, Mighty and Majestic is He, and success in meeting Him, which cannot be attained except in the Hereafter.

It is also said: We have chosen them by granting them success for it and by being kind to them in choosing it. The ba here, as in the first interpretation, is for causality. The expression is similar to your saying: "I honored him for his knowledge," meaning: I honored him because he is knowledgeable, or I honored him because I made him knowledgeable. It might be imagined in the second case that it is a silah (connective particle). The first interpretation is supported by the reading of al-A‘mash and Talhah: bi-khalisatihim (by their pure quality).

Ibn al-Mundhir narrated from al-Dahhak that the "remembrance of the Abode" means their reminding those who have forgotten the Hereafter, encouraging them toward it, and turning them away from worldly desires in a manner free from egoistic motives, as is the way of the Prophets, peace be upon them.

It is also said that the intended meaning of "the Abode" is this worldly life, and "remembrance of it" refers to the beautiful praise and the tongue of truth that belongs to no one but them. This was reported from al-Jubba’i and Abu Muslim, and Ibn ‘Atiyyah mentioned it as a possibility. The gist of the verse according to this view, as al-Tabarsi stated, is: "Indeed, We have distinguished them with beautiful mention among those who come after."

Abu Ja‘far, Shaybah, al-A‘raj, Nafi‘, and Hisham read it with the genitive construction (idafa) of khalisatu to dhikra as an explicative, meaning: with that which has been purified from the remembrance of the Abode—in the sense that they do not mix its remembrance with anything else at all, or other such meanings. It is also permissible, according to this reading, for khalisah to be an infinitive, like al-‘aqibah and al-kadhibah, annexed to its agent, meaning: We have chosen them in that the remembrance of the Abode has become exclusively theirs. The apparent view of Abu Hayyan is that the possibility of it being an infinitive is also plausible in the first reading, though he stated: "The most apparent view is that it is an active participle."