Tafsir of At-Tariq 86:9

"The Day when secrets are tested," meaning when that which was concealed within hearts—such as beliefs, intentions, and other matters, as well as what was hidden of deeds—is examined and scrutinized, and distinction is made between that which is pure among them and that which is foul. The root of al-ibtila' (testing/trial) is al-ikhtiyar (selection/examining), and its application to what has been mentioned is an application to its consequence. Taking the term "secrets" in its general sense is the apparent meaning. Ibn al-Mundhir recorded from ‘Ata’ and Yahya ibn Abi Kathir that it refers to fasting, prayer, and washing from major ritual impurity (janabah). Al-Bayhaqi recorded in al-Shu’ab from Abu al-Darda’ that the Messenger of Allah (may Allah bless him and grant him peace) said: "Allah has guaranteed His creation four things: prayer, zakat, fasting Ramadan, and washing from major impurity; these are the secrets which Allah the Exalted referred to when He said: 'The Day when secrets are tested.'" He included monotheism with them. Perhaps the intent is to state their greatness by way of exaggeration, not to actually limit the meaning. Al-Hasan heard someone reciting the poem of al-Akhwas: "There shall remain in the hidden depths of the heart and the gut, a secret, on the Day when secrets are tested." He said, "How heedless he is of what is in the heaven and the Night-Comer!" It is as if he interpreted the "remaining" therein as referring to the original examination; so understand this.

"The Day," according to a group of skilled grammarians, is an adverbial modifier for a deleted verb indicated by what precedes it, meaning: "He will return him [on] the Day..." Others, such as al-Zamakhshari and a group, said it is an adverbial modifier for "His return" (ruj’ihi). This was objected to on the grounds that it separates the noun from its complement with an extrinsic element. It was answered at times by saying this is permissible due to the flexibility they allow regarding adverbial modifiers, and at other times by saying the separator here is not extrinsic because it is either an explanation or an agent according to both schools of thought. 'Isam al-Din said that the separation by this extrinsic element is as if it were no separation at all, because the complement is intended to be placed before it, and was only delayed to observe the rhyme scheme; this is a matter that is not hidden.

It has also been said that it is an adverbial modifier for "helper" after it. Abu Hayyan critiqued this, calling it corrupt, because what comes after the fa (the particle of response) cannot act upon what precedes it, and similarly, the negative ma according to the well-known, supported view. It has also been said that it is the complement of a deleted "remembrance." It is as you see. This, or the previous option, is necessary according to the opinion of Mujahid and ‘Ikrimah, and the aforementioned opinion of al-Dahhak. Al-Tabarsi permitted its connection to "Capable" (Qadir), but the majority of grammarians did not connect it to that because it implies that His power (Exalted be He) is exclusive to one day and not another, as stated by more than one. Ibn ‘Atiyyah said they fled from the agent being "Capable" because it necessitates restricting power to that day alone. Yet, when the meaning and what the eloquent speech of the Arabs requires are contemplated, it is permissible for it to be the agent. This is because the Exalted said, "Indeed, He is able to return him" in an absolute sense, earlier and later, and at all times. Then, the Exalted mentioned among the times the greatest time for the disbelievers, because it is the time of requital and arrival at the punishment, so that people may gather in caution of it and fear of it. This is the conclusion, and despite what it contains, it does not dispel the implication.