Bukhari

Hadith Commentary:
It was pouring rain when the time for Jumu‘ah arrived, and the mu’adhdhin began the call to prayer (adhan). When he reached “Hayya ‘ala as-salah,” Abdullah ibn Abbas (radi Allahu anhu) immediately prompted him to say, “As-salatu fi ar-rihal,” meaning, “O people, perform the prayer in your dwellings.”
Since this was something new for the people, they were surprised.
Upon this, Ibn Abbas (radi Allahu anhu) explained to them that he had seen the Messenger of Allah (sallallahu alayhi wa sallam) do the same in such circumstances.
It is thus understood that on such special occasions, it is permissible to speak during the adhan.
And if, by coincidence, someone laughs during the adhan, this too will not invalidate the adhan.
These are incidental matters through which Islam intends to show ease and facilitation.

Hadith Commentary:
(1)
In this narration, there is no explicit mention of the mu’adhdhin (caller to prayer) speaking during the adhan (call to prayer), so its relevance to the chapter heading is as follows: speaking during the adhan affects the sequence and style of the words of the adhan. Saying "Ala sallu fi r-rihal" after "Hayya ‘ala as-salah" or in its place also affects the customary style of the adhan, but even so, the adhan remains valid. Imam Bukhari rahimahullah’s intent is also this: if, during the adhan, such speech occurs that affects the order of the adhan, it does not invalidate the correctness of the adhan.

(2)
At the end of the narration, we have added "Friday prayer" in parentheses during translation, because in a narration reported from Ibn Abbas radi Allahu anhu, this is explicitly mentioned. (: Sahih al-Bukhari, al-Jumu‘ah, Hadith: 901) This means that if the words "Ala sallu fi r-rihal" are said, then in view of "Hayya ‘ala as-salah," it is necessary to attend the Friday prayer despite rain and mud, even if hardship must be endured. The meaning of saying "Ala sallu fi r-rihal" is that rain is such an excuse due to which a strict ruling (azimah) is changed into a concession (rukhsah). (: Fath al-Bari: 2/494)

(3)
Should the words "Ala sallu fi r-rihal" be said in place of "Hayya ‘ala as-salah," after it, or after the completion of the adhan due to rain or mud? The details and the preferred opinion regarding this will be explained under Hadith: 632.

Benefits:

➊ Ibn Abbas radi Allahu anhuma instructed the mu’adhdhin to say «اَلصَّلَاةُ فِي الرِّحَالِ» in place of «حَيَّ عَلَى الصَّلَاةِ، حَيَّ عَلَى الْفَلَاحِ» during the adhan, which is not a daily part of the adhan. From this, the permissibility of speaking during the adhan is established.

➋ «إِنَّهَا عَزْمَةٌ:»—that is, coming for Jumu‘ah upon hearing the adhan—is an obligation (azimah), because Allah the Exalted has said: «يَاأَيُّهَا الَّذِينَ امَنُوا إِذَا نُودِيَ لِلصَّلوة مِنْ يَوْمِ الْجُمُعَةِ فَاسْعَوْا إِلى ذِكرِ اللهِ وَذَرُوا الْبَيْعَ» [الجمعة: 9] (“O you who have believed! When the call is made for prayer on the day of Jumu‘ah, hasten to the remembrance of Allah and leave off trade.”) If I had instructed to say «حَيَّ عَلَى الصَّلَاةِ», then attending Jumu‘ah would have become obligatory for everyone, and coming in the mud would have caused them hardship. Therefore, I instructed to say «الصَّلَاةُ فِي الرِّحَالِ», that you should pray in your homes; now there is a concession—whoever wishes may come, and whoever wishes may not come.

➌ Whether the words «اَلصَّلَاةُ فِي الرِّحَالِ» or «أَلَا صَلُّوْا فِي الرِّحَالِ» are said in place of «حَيَّ عَلَى الصَّلاةِ» or are said at the end after the entire adhan, both ways are permissible. The hadith regarding saying it afterwards is coming up (632), and that is what is commonly practiced.

➍ مَنْ هُوَ خَيْرٌ مِنْهُ:
That is, this is how that mu’adhdhin did who was better than this mu’adhdhin, meaning the mu’adhdhin of the Prophet sallallahu alayhi wa sallam did so, who was certainly better than this mu’adhdhin. In one version of Sahih Bukhari, the wording is: «مَنْ هُوَ خَيْرٌ مِنْيْ», meaning: “This was done by the one who is better than me,” that is, the Messenger of Allah sallallahu alayhi wa sallam instructed the mu’adhdhin in this way, who was better than me.