Tafsir of Al-Isra 17:20

(Kullan): According to the majority of grammarians, the tanwin herein serves as a substitute for an omitted genitive (mudaf ilayhi), not as a tanwin of manifestation (tamkin). That is, both parties. It is the object of the verb "numiddu" (We extend), placed before it. This means: We extend them time and again, such that the subsequent extension is an addition to the preceding one. That by which the extension occurs is what has been hastened for one of them in terms of immediate gifts, and what has been prepared for the other in terms of future gifts, alluded to by "the striving being appreciated." It was not explicitly stated, relying upon what preceded it in both explicit and implicit forms, and leaning upon what followed it in phrasing and indication.

His saying, (ha’ula’i wa ha’ula’i): These are in substitution (badal) for "kullan," a substitution of the whole, for the sake of detailing. That is: We extend these—those for whom it is hastened—and those—those whose striving is appreciated. For the indication (ishara) addresses the essence of the referred-to entity along with its specific title, not merely the essence alone, as is the case with pronouns (idmar). Thus, it contains a reminder of that by which the extension occurs, and a specification of the omitted genitive, to dispel the illusion that it refers only to the individuals of the latter group—those who desire the good and are truly worthy of assistance—as well as an emphasis on the restriction (qasr) derived from the advancement of the object.

His saying, (min ‘ata'i rabbik): That is, from His expansive giving which has no end. It is a verbal noun (ism masdar) placed in the position of a passive participle (ism maf’ul), related to "numiddu," serving to make mentioning that by which the extension occurs unnecessary, and signaling that the aforementioned extension is not by way of entitlement through striving and action, but by pure grace. As it is said: "And the giving of your Lord" (whether it be worldly or otherworldly). The use of the explicit noun in place of a pronoun is to show greater care for its status and to signal its causality for the ruling.

(Mahzura): Forbidden to those who desire it. Rather, it flows upon those for whom it is destined by the necessity of the Will, which is built upon Wisdom, even if there is found within it that which would necessitate restriction, such as disbelief. This is in the sense of a justification for the extension’s encompassment of both groups. The address by the title of Lordship (Rububiyyah) is to signal its foundational role in both the extension and the lack of restriction.