Tafsir of As-Saffat 37:112

This is a "prospective state" (ḥāl muqaddarah), similar to His saying: "Enter it, abiding eternally" (Az-Zumar: 73).

If you ask: There is a difference between this and "Enter it, abiding eternally." In the latter, the entry exists at the time of the action, and while the "abiding" does not exist at that exact moment, it is intended as "destined to abide." This is straightforward. However, the one being given glad tidings—Isaac—was non-existent at the time of the glad tidings. The non-existence of the subject necessitates the non-existence of his state, for a state is an adornment, and an adornment cannot exist without the adorned. Furthermore, when Isaac was eventually born, prophethood did not exist with him; it was delayed for a long time. How, then, can "as a prophet" be a prospective state? A state is a description of the agent or object at the time the action occurs. While "abiding" is their description upon entering Paradise, "prophethood" cannot be considered existing or prospective at the time of the glad tidings because Isaac himself did not exist.

I say: This is a subtle question with a narrow path. What resolves the difficulty is the necessity of assuming an omitted genitive construction (muḍāf). It is as if you said: "We gave him glad tidings of the existence of Isaac as a prophet," meaning: "that he would exist, with his prophethood being prospective." Thus, the governing agent of the state is the "existence," not the act of giving glad tidings. In this way, it returns to the analogy of His saying: "Enter it, abiding eternally."

{من الصالحين} (Among the righteous): This is a second state, mentioned by way of praise and commendation, for every prophet must necessarily be among the righteous.

Regarding Qatadah’s view: God gave him glad tidings of Isaac’s prophethood after He tested him with his slaughter. This is the response of those who hold that the one to be slaughtered was Isaac, addressing the objection regarding the verse: "And We gave him glad tidings of Isaac." They argue: It is not permissible for God to give him glad tidings of his birth and his prophethood simultaneously, because the test of slaughtering him would not be valid if he knew he would become a prophet.

{وباركنا عليه وعلى إسحاق} (And We blessed him and Isaac): It is also read as wa-baraknā. It means: We bestowed upon them both the blessings of this world and the Hereafter, similar to His saying: "And We gave him his reward in this world, and indeed, in the Hereafter he will be among the righteous" (Al-Ankabut: 27). It is also said: We blessed Abraham through his children, and blessed Isaac by bringing forth the prophets of the Children of Israel from his loins.

{وظالم لنفسه} (And one who is a wrongdoer to himself): Its parallel is: "He said, 'My covenant does not include the wrongdoers'" (Al-Baqarah: 124). In this is a warning that the state of the wicked and the righteous does not follow lineage or ancestry; the righteous may beget the wicked, and the wicked may beget the righteous. This demolishes the notion of innate natures and elements. It also indicates that wrongdoing among their descendants does not reflect as a defect or deficiency upon them (the ancestors), and that a person is blamed for his own evil deeds and held accountable for what his own hands have committed, not for what is found in his origin or his offspring.