Tafsir of Saba' 34:20

"And indeed Iblis had proven his assumption against them" (i.e., he realized his assumption against them, or found his assumption to be true).

The apparent meaning is that the pronoun "against them" refers to the people of Saba'. The source of his assumption was seeing their immersion in desires. It has been said: it refers to the children of Adam, and the source of his assumption was his observation of their father, Adam (peace be upon him), as he had listened to his whisperings, so he compared the branch to the root and the child to the parent. It has also been said: he realized the desire and anger implanted within them, both of which are the sources of evils. Another view is that this originated from hearing the words of the angels (peace be upon them): "Will You place therein those who will cause corruption and shed blood?" on the day the Exalted said to them: "Indeed, I will make upon the earth a successor." It is also possible that the source of this was his own inherent evil, as it is said: "If a person's conduct is evil, his assumptions become evil," and he confirms what he is accustomed to imagining. It is permissible that all the mentioned factors were the source of his assumption regarding Saba'. The discourse, based on the first interpretation of the pronoun—as al-Tayyibi stated—is a continuation of what preceded it, either as a state (hal) or a conjunction; based on the second, it is like a conclusion (tadhyil) for emphasis.

The Basrans read saddaqa (with a tashdid/emphasis), and thus zannahu (his assumption) is in the accusative case due to the elision of the preposition; the original meaning is saddaqa fi zannihi (he was proven right in his assumption), meaning he found his assumption to be correct in reality. Thus, saddaqa in this context means "to be correct" metaphorically.

It is said that it is in the accusative as a verbal noun (masdar) for an implied verb; i.e., yazunnu zannahu (he assumes his assumption), like the expression fa'altahu jahdaka (you do your utmost/effort). The sentence occupies the position of a state, and saddaqa is interpreted as previously mentioned. It is also permissible for it to be in the accusative as a direct object, with the verb being transitive to it directly because siddq (truth/veracity) originally applies to speech, and speech is among those things that take a direct object. The meaning is: he realized his assumption, as in the Hadith: "He fulfilled (saddaqa) His promise and gave victory to His servant," and the saying of the Exalted: "Men who fulfilled (sadaqu) what they pledged to Allah."

Zayd ibn Ali, Ja'far ibn Muhammad, al-Zuhri, Abu al-Jahjah al-A'rabi (one of the eloquent Arabs), and Bilal ibn Abi Burza read it with Iblisu in the nominative and zannuhu in the nominative. This is how it is mentioned in al-Bahr. The one who assumes this (with the reading of saddaqa with tashdid) means that he found his assumption to be true. However, Ibn Jinni mentions that al-Zuhri used to read it with the light sadaqa (takhfif), meaning: "He spoke the truth to him when he tempted him into misguidance."

'Abd al-Warith, from Abu 'Amr, read Iblisu zannahu with both in the nominative, making the second a substitute of inclusion (badal al-ishtimal). Al-Zamakhshari kept the reader ambiguous, saying: "It was read with light sadaqa and both in the nominative, with the meaning: 'The assumption of Iblis was proven true against them.'" If it were read with tashdid while both were in the nominative, it would be for the sake of intensification in saddaqa, similar to the verse: "My soul and what my right hand possessed were sacrificed, (for) horsemen whose truthfulness my assumptions confirmed." This clearly shows that no one read it in that manner, and Allah knows best. In all readings, "against them" (alayhim) relates to the preceding verb and does not relate to the "assumption" in any of them.

"And they followed him"—that is, the people of Saba', or it is said, the children of Adam—"except a party of the believers"—that is, except a party who are the believers; they did not follow him. "From" (min) is explanatory. Their small number is either because they are few in themselves or because they are few in comparison to the disbelievers; the latter is definitive according to the view that the pronoun refers to the children of Adam. I imagine you would choose that the small number refers to them in themselves according to the view that the pronoun refers to Saba', due to the lack of prevalence of the multitude of believers among them. Or, it means "except a party of the groups of believers," and they are the sincere ones, where "from" (min) denotes partiality. The intention is absolute following, which is broader than disbelief.