Tafsir of Al-Muzzammil 73:5

"Indeed, We shall cast upon you": That is, We shall reveal to you. The preference for the term "casting" (al-ilqa') over others is due to the statement of the Exalted, "a weighty word," which is the Magnificent Quran. Because of the burdensome obligations it contains for the accountable, especially for the Messenger—may the blessings and peace of Allah be upon him—for he, peace and blessings be upon him, was commanded to bear them and to impose them upon the nation.

This emphasized sentence is a parenthetical clause between the command to stand [in prayer] and the explanation of it that follows, intended to facilitate the burden of standing [in prayer] that was placed upon him, peace and blessings be upon him. It is as if it were said: "Weights of burdensome obligations will soon descend upon you in the revealed revelation; therefore, this [standing in prayer] is easy in comparison to it. So, do not be concerned by this difficulty, and train yourself through it for what is to come after it"—the objection to this being the clause "And recite," etc.—though it has been argued that there is no basis for this [interpretation].

It has been said that its being "weighty" means it is profound in the firmness of its structure and the solidity of its meanings. The intent is that it outweighs everything else in wording and meaning, but the word "weighty" is used metaphorically for "preponderant," as that which is preponderant naturally possesses this quality. Similar in meaning is the view that it refers to speech that has weight and significance, not something trivial.

It is also said that it is weighty for the one who contemplates it, due to its need for profound spiritual purification and focused intellectual inquiry; thus, "weighty" is a metaphor for "difficult." Others say it is weighty in the Scale, and "weighty" is either literal or a metaphor for the abundance of the reward for its reciter. Abu al-Aliyah and al-Qurtubi stated that its weightiness is upon the disbelievers and the hypocrites due to its miraculous nature and its warnings.

It is also said that it is weighty to receive, meaning it weighed heavily upon him—may the blessings and peace of Allah be upon him—when the revelation came to him through the Angel. For the revelation would come to him, peace and blessings be upon him, in various ways. Among these was that the Angel would not manifest himself to him and speak, but rather a state would come upon him, peace and blessings be upon him, like a swoon, due to the intense attraction of his noble soul toward the High Assembly, such that he would hear what was revealed to him, witness it, and perceive it—he, peace and blessings be upon him—to the exclusion of those with him. In this state, he would feel a weight in his body, to the extent that his thigh, may the blessings and peace of Allah be upon him, would almost crush the thigh of Zayd ibn Thabit while it was upon his own during the revelation.

Ahmad, ‘Abd ibn Humayd, Ibn Jarir, Ibn Nasr, and al-Hakim—who authenticated it—narrated from ‘Aishah that when the Prophet, may the blessings and peace of Allah be upon him, received revelation while he was on his camel, it would place its chest [on the ground] and be unable to move until the state passed from him. Then, "Indeed, We shall cast upon you a weighty word" was revealed. The two Shaykhs, Malik, al-Tirmidhi, and al-Nasa'i narrated from her that she said: "I saw him when the revelation descended upon him on an intensely cold day; when it ceased, his forehead was streaming with sweat."

According to this perspective, it is permissible for "weighty" (thaqilan) to be an adjective for a deleted verbal noun (masdar) that was replaced by its own position, thus being in the accusative case as the noun was; that is, "a weighty casting," and not an adjective for "a word" (qawlan).

It is also said that this refers to its remaining throughout the ages, for it is the nature of the "weighty" to remain in its place. Others say it is weighty in consideration of the weight of its letters, literally, in the Preserved Tablet. It is narrated from some that every letter of the Quran in the Tablet is greater than the mountain of Qaf, and that if the angels were to gather to lift a single letter, they would not be able to do so until Israfil, peace be upon him—the Angel of the Tablet—came and lifted it and carried it by the permission of Allah—not by his own strength—though the Mighty and Majestic [God] empowered him to do so. This is a matter that requires authentic transmission from the Truthful [Prophet], peace be upon him, and I do not think such a report exists.

The sentence, according to most of these views, is an incipit for the purpose of giving a reason, for the night prayer prepares the soul to handle the weight of the [revelation]; so contemplate this. It has been inferred from the verse that one should not say "a light Surah," because Allah, the Exalted, has named the entire Quran "a weighty word" within it. This is a matter of caution, as is not hidden.