Tafsir of Ta-Ha 20:86

(Then Moses returned to his people) at his known time of return, that is, after he had completed the forty days of Dhu al-Qa'dah and the ten [days] of Dhu al-Hijjah and received the Torah, not immediately following the aforementioned news. The causality of what precedes the fa (then) for what follows it is only by consideration of the condition of returning derived from His saying, Exalted is He: (angry and sorrowful), not by consideration of the [news] itself, even if it is grammatically linked to it. For the fact that the return was after the completion of the forty days is a settled and well-known matter; no one’s imagination would wander to the notion that it occurred at the time of the aforementioned news. Just as if you were to say: "I bid farewell to the pilgrims and prayed for their safety, so they returned safe," no one would doubt that what is meant is their customary return, not their return immediately following the prayer, and that the causality of the prayer is in consideration of the description of safety, not the return itself. This is how it is stated in Irshad al-'Aql al-Salim, and it is a matter upon which no two rams would butt heads.

Al-Asaf (sorrow) is extreme sadness, as narrated from Ibn Abbas. His sorrow, peace be upon him, was because of what his people had fallen into, which would entail punishment, and he could not avert it from them. Many said: It is intense anger. Al-Jubba'i said: It is regret for what he missed, confused about the affair of his people, fearing that he might not be able to rectify it; this is a less common meaning for al-asaf.

(He said) is a narrative resumption as if it were said: What did he do to them when he returned to them? It is said: He said: (O my people, did your Lord not promise you...) The interrogative particle is for the denial of the lack of a promise and the negation thereof, and for confirming its existence in the most eloquent and emphatic manner; i.e., did He not promise you (a good promise) which you have no way to deny? What is meant by that is the granting of the Torah, in which there is guidance and light. It is also said: It is what He, Glory be to Him, promised them of reaching the right side of the Mount, and what followed that of conquests in the land, forgiveness for those who repented and believed, and other things that God Almighty has promised the people of His obedience.

From Al-Hasan: The good promise is Paradise, which He promised to those who hold fast to their religion. It is also said: It is that He, Great and Majestic is He, lets them hear His speech. Perhaps the first is more appropriate. The accusative case of (a promise) is possible as a second object, meaning the "promised thing," or it may be an infinitive, with the second object omitted. The fa in His saying: (Did the period seem too long for you?) is for conjunction with an implied [verb], and the interrogative is for the denial and negation of the conjoined element alone. It is permitted that the interrogative be moved from a later position because of its priority, and that the conjunction be upon "did not promise you," because it is in the sense of "He has indeed promised you." A group chose the first. The al (definite article) in "the period" refers to the time of fulfillment. It is also said: the time of separation; i.e., did He, Glory be to Him, promise you that, and did the time of fulfillment or the time of separation for its arrival seem too long for you?

(Or did you desire that wrath) i.e., punishment, (from your Lord descend upon you?) i.e., from the Master of your affair absolutely. The intent of "desiring" that is the doing of that which necessitates it. The fa in His saying (so you broke my appointment) is for the sequencing of what follows it upon each of the two parts. "Appointment" is an infinitive attributed to its object to emphasize the ugliness of their situation, for their breaking of the promise that existed between them and him, peace be upon him—in view of its attribution to him, peace be upon him—is more heinous than in view of its attribution to them. The meaning is: Did the time seem long to you, so you forgot because of that, and thus you broke your promise to me to remain steadfast in my religion until I return from the appointed time, out of forgetfulness? Or did you intentionally do what would be a cause for the descent of your Lord's wrath upon you, and thus you broke your promise to me by that intentionally? The conclusion is: Did you forget and thus break [it], or did you intend and thus break [it]? From this, the contrast between the two parts is known.

Al-Mufaddal permitted that "appointment" be an infinitive attributed to the subject, and his breaking it means he found it to be broken; it is said: "He broke Zayd's promise," meaning he found it broken. Its likeness is "I praised Zayd," i.e., I found it praiseworthy. So you found the breaking of my promise to you after the forty days. The objection to this is that the context and the preceding text do not support it at all. It is said: The infinitive is attributed to the object, but what is meant by it is their promise to him, peace be upon him, to follow him and come to the Mount after him, and there is what is in that [interpretation]. The Mu'tazilah argued from the verse that God, Great and Majestic is He, is not the Creator of disbelief, otherwise He, Glory be to Him, would not have said, "And the Samiri led them astray." And there is a facet to Moses's anger and sorrow, and the weakness of that [argument] is not hidden.