Explanation of the author's statement: "… and covering his 'awrah (part of the body that must be covered) is sufficient in voluntary prayer, and covering one of his shoulders is required in obligatory prayer…"

The Shaykh : He said: "and covering his 'awrah (part of the body that must be covered) is sufficient in voluntary prayer".
"Covering his 'awrah (part of the body that must be covered) is sufficient" means the man's 'awrah (part of the body that must be covered) "in voluntary prayer", which is the area between the navel and the knee, except for a boy aged seven to ten, for whom it is what? The two private parts, the front and the back. Covering the 'awrah (part of the body that must be covered) is sufficient, and as for covering more than that, it is a recommended practice (sunnah).
He said: "in voluntary prayer", meaning other than obligatory prayer, because obligatory prayer requires an additional covering; it requires an increase in covering the 'awrah (part of the body that must be covered).
Voluntary prayer is everything other than obligatory prayer. Now, obligatory prayers are of two types: a prayer restricted by time and a prayer restricted by a cause. A prayer restricted by time is like the five daily prayers—are the rawatib (the regular voluntary prayers attached to the obligatory ones) obligatory or voluntary? Yes, the rawatib (the regular voluntary prayers attached to the obligatory ones) are obligatory! Voluntary. We are talking now about the obligatory prayer—the five daily prayers and Jumu'ah (the Friday prayer), right? And we can say the prayer of the two festivals, according to the opinion that it is obligatory, and a prayer restricted by a cause, like the funeral prayer (janazah). The funeral prayer has no specific time, but it is restricted by a cause, and it is obligatory, but it is a collective obligation (fard kifayah), as is well known.
The important point is that in voluntary prayer, covering the 'awrah (part of the body that must be covered) is sufficient. As for the obligatory prayer, the author said: "and covering one of his shoulders is required in obligatory prayer". The shoulder (the area where the cloak is placed) is the place on the neck where the cloak is put. You place the cloak like this, so the cloak is positioned between the shoulder and the neck; this is the shoulder. So in obligatory prayer, you must add to covering the 'awrah (part of the body that must be covered) the covering of one of the two shoulders, either the right or the left. This is in obligatory prayer.
So, what is the evidence? The evidence is the saying of the Prophet (peace and blessings be upon him) and in one wording in the dual form and the dual form does not contradict the singular, because the singular is attached (to a noun), and what is attached is general. So the apparent meaning of the hadith is that it is necessary to cover both shoulders, to cover both shoulders. And this hadith is more general than, meaning the evidence is more general than the meaning, because the evidence says and this includes the obligatory and the voluntary. So our using the more general to argue for the more specific is a deficiency in acting upon the hadith or the text. Why is it a deficiency? Because if a hadith or text indicates a general ruling in general terms, and then you restrict it to some of its instances, that is a deficiency in acting upon it. Since the general must, as we have passed through in the principles of jurisprudence, what must be done? It must be acted upon in its generality. It must be acted upon in its generality except with evidence. And there is no evidence in this issue. Therefore, we say that arguing with the hadith requires that it be acted upon in its generality, because the hadith is general .
Now, in the author's statement, he distinguishes between obligatory and voluntary prayer, and this is one of the differences between obligatory and voluntary prayer. There are more than twenty differences, meaning between the obligatory prayer and the voluntary prayer, there are more than twenty differences. Perhaps you will follow up on this, if Allah wills, right?

The questioner : We wrote it down, O Shaykh.

The Shaykh : You wrote it down.

The questioner : Yes, ...

The Shaykh : Fine, now, in any case, this is one of the points. So the ruling according to the school of jurisprudence (madhhab) is that covering the 'awrah (part of the body that must be covered) is sufficient in voluntary prayer, and in obligatory prayer, covering one of the shoulders is added to covering the 'awrah (part of the body that must be covered). And the evidence? And I told you that this evidence is more general than the ruling, so acting upon it, if we restrict it to some of its instances, is acting upon it in a deficient way. Just as the hadith says: and the author says "with one of his shoulders." If we took the evidence, we would say that both shoulders are obligatory. And what the author adopted is the well-known position of the school of jurisprudence (madhhab).
The second opinion is that covering one of the shoulders, covering the shoulders, is a recommended practice (sunnah) and not obligatory, based on the hadith: And this opinion is the stronger position (rajih). But is it necessary that there be something of the garment on the shoulders because the shoulders are 'awrah (part of the body that must be covered), or because of the completeness of the clothing and tightening the waistcloth? Because if you do not tighten it on your shoulders, it might slip off and fall? So the intended meaning is that covering the shoulders here is intended for something else, not intended for itself. The issue is possible, but the obligation of covering the shoulders or one of them, according to the author's statement, is questionable. The correct view is what the majority of scholars have adopted, which is that covering the shoulders or one of them is on the basis of recommendation (mustahabb).