Nasai

In the previous ahadith, the mention of expiation (kaffarah) comes before breaking the oath, whereas in this hadith (and the forthcoming ahadith), breaking the oath is mentioned first and expiation afterwards. Thus, both are permissible. There is no explicit statement making either sequence obligatory. If one particular method were necessary, the Prophet (sallallahu alayhi wa sallam) would have explicitly instructed to adopt it, but he did not do so. In any case, this is the position of the majority of the scholars, and it is the correct one. Acting upon authentic ahadith is far better than acting upon analogical reasoning (qiyas).

Hadith Commentary: Benefits and Issues:
From the hadiths mentioned in this chapter, it is established that when the mu’adhdhin begins the iqamah for prayer, after that no prayer can be performed except the one that is to be offered in congregation behind the imam. According to the majority, it is not permissible to begin any voluntary (nafl) or sunnah prayer after the iqamah has started.

As for the prayer that a person was already performing, if he has passed the bowing (ruku‘) of the last rak‘ah, then he should complete it; otherwise, he should leave it. This is because, from the narration of Abdullah bin Malik radi Allahu anhu, it is understood that a person was performing the sunnah of Fajr, and then the iqamah was given. When the Prophet sallallahu alayhi wa sallam saw him praying, he said, “Will you pray four rak‘ahs of Fajr?” It appears that after the iqamah, he still had both rak‘ahs left to pray. However, according to the Hanafis, since great emphasis has been placed on the sunnah of Fajr, if a person can join the imam in the second rak‘ah, then he may perform the sunnah of Fajr after the iqamah. But in the narration of Abdullah bin Sarjis radi Allahu anhu, there is explicit prohibition of performing the sunnah of Fajr in the mosque after the iqamah. For this reason, Allamah Sa‘idi writes:

Apparently, this hadith supports Imam Shafi‘i rahimahullah, because the Prophet sallallahu alayhi wa sallam himself emphasized the sunnah of Fajr, yet he himself expressed displeasure at performing the sunnah after the iqamah of Fajr.

Therefore, following the hadith requires that one should not begin the sunnah prayer at the time of the iqamah for Fajr (because the one by whose command the sunnah is performed is himself prohibiting it). And if the sunnah prayer has already been started, then it should be completed as quickly as possible and one should join the congregation. Allamah Dashtani writes that Umar radi Allahu anhu used to strike the person who performed the sunnah at the time of the iqamah for Fajr, because the Prophet sallallahu alayhi wa sallam prohibited this.

(Sahih Muslim, vol. 2, p. 421)

He further writes:

This extremely incorrect practice is prevalent that when the congregation for Fajr is standing in the mosque, people begin to perform the sunnah prayers standing adjacent to the rows of the congregation. One problem with this is that the imam is reciting the Qur’an aloud, listening to which is obligatory, and the person engaged in the sunnah is neglecting this obligation. The second problem is that the person engaged in the sunnah is, outwardly, turning away from the obligatory prayer and the congregation. The third problem is that this action necessarily entails opposition to the hadiths of this chapter.

(vol. 2, p. 421)