Tafsir of Al-Hijr 15:40

{Except for Your chosen servants among them.}

(The word al-mukhlaseen) with a fatḥah on the lām is the recitation of the Kufans, Nafi‘, al-Ḥasan, and al-A‘raj. It means: those whom You have chosen for Your obedience and purified from everything that contradicts that. Although the apparent [expression] would have been, for example, "and among them are those whom I will not lead astray," the discourse turned away from it to what was mentioned [i.e., al-mukhlaseen] because sincerity and pure devotion to Allah Almighty necessitates that [salvation from being led astray]. Thus, it is a case of mentioning the cause while intending its effect and its necessary consequence by way of metonymy (kināyah), and it contains the affirmation of a thing through its proof, making it an explicit statement of it.

The remaining seven [reciters] and the majority read it with a kasrah on the lām (al-mukhliseen), meaning: those who have made their deeds sincere for You and have not associated anyone with You in them.