Bukhari

Hadith Commentary:

It is evident from the chapter and the transmitted hadith that the imam, in case of necessity, may supplicate for rain (istisqa) during the Friday sermon (khutbah). It is also established that, during the sermon, a request can be made to the imam to supplicate for any public need, and that the imam may attend to such a request within the sermon itself.

Those scholars who have considered the sermon to be on the level of prayer and thus have prohibited speaking during it, even in times of necessity, are shown by this hadith to be incorrect in their view.

Allamah Shawkani writes regarding this incident:

“And in the hadith are benefits:
Among them is the permissibility of conversation from the preacher during the sermon, the repetition of supplication, the inclusion of the prayer for rain (istisqa) in the Friday sermon, supplicating for it upon the pulpit, omitting the turning of the cloak and facing the qiblah, and sufficing with the Friday prayer in place of the prayer for rain, as has preceded. And in it is a sign from the signs of prophethood, in Allah the Exalted answering the supplication of His Prophet and the clouds obeying his command, as has occurred in many narrations, and other benefits.” (Nayl al-Awtar)

That is, many rulings are derived from this hadith, for example: the permissibility of speaking to the preacher during the sermon, as well as supplicating (and raising the hands for supplication); and the supplication for rain (istisqa) during the Friday sermon; and omitting the turning of the cloak and not facing the Ka‘bah on such an occasion; and considering the Friday prayer sufficient in place of the prayer for rain (salat al-istisqa); and in this is an important proof of your prophethood, that Allah the Exalted accepted your supplication and commanded the clouds to obey your order; and there are many other benefits as well.

With what words did you supplicate for rain (istisqa)?

There are also several narrations regarding this, among which the comprehensive supplications are as follows:
{الْحَمْدُ لِلَّهِ رَبِّ الْعَالَمِينَ} [الفاتحة: 2] {الرَّحْمَنِ الرَّحِيمِ} [الفاتحة: 3] {مَالِكِ يَوْمِ الدِّينِ} [الفاتحة: 4]
Lā ilāha illā Allāh, yaf‘alu Allāhu mā yurīd. Allāhumma anta Allāh, lā ilāha illā anta.

Allamah Shawkani writes regarding this incident:

“And in the hadith are benefits:
Among them is the permissibility of conversation from the preacher during the sermon, the repetition of supplication, the inclusion of the prayer for rain (istisqa) in the Friday sermon, supplicating for it upon the pulpit, omitting the turning of the cloak and facing the qiblah, and sufficing with the Friday prayer in place of the prayer for rain, as has preceded. And in it is a sign from the signs of prophethood, in Allah the Exalted answering the supplication of His Prophet and the clouds obeying his command, as has occurred in many narrations, and other benefits.” (Nayl al-Awtar)

That is, many rulings are derived from this hadith, for example: the permissibility of speaking to the preacher during the sermon, as well as supplicating (and raising the hands for supplication); and the supplication for rain (istisqa) during the Friday sermon; and omitting the turning of the cloak and not facing the Ka‘bah on such an occasion; and considering the Friday prayer sufficient in place of the prayer for rain (salat al-istisqa); and in this is an important proof of your prophethood, that Allah the Exalted accepted your supplication and commanded the clouds to obey your order; and there are many other benefits as well.

With what words did you supplicate for rain (istisqa)?

There are also several narrations regarding this, among which the comprehensive supplications are as follows:
{الْحَمْدُ لِلَّهِ رَبِّ الْعَالَمِينَ} [الفاتحة: 2] {الرَّحْمَنِ الرَّحِيمِ} [الفاتحة: 3] {مَالِكِ يَوْمِ الدِّينِ} [الفاتحة: 4]
Lā ilāha illā Allāh, yaf‘alu Allāhu mā yurīd. Allāhumma anta Allāh, lā ilāha illā anta, anta al-ghaniyyu wa naḥnu al-fuqarā’, anzil ‘alaynā al-ghayth, waj‘al mā anzalta lanā quwwatan wa balāghan ilā ḥīn.
Allāhumma isqina ghaythan mughīthan marī’an marī‘an ṭabaqan ghadqan ‘ājilan ghayra rā’ith.
Allāhumma isqi ‘ibādaka wa bahā’imaka wa anshur raḥmataka wa aḥyi baladaka al-mayyit.

It is also a prescribed matter that, on such occasions, a pious elder from among the people should be brought forward to supplicate, and he should beseech Allah with tears, and the people behind him should say “Amin, Amin” and, with humility and earnestness, ask Allah for rain.

Hadith Commentary:
(1)
From this hadith, it is understood that during the sermon (khutbah), it is permissible to request the imam to supplicate (make du'a) for a public need, and the imam may act upon such a request even during the khutbah itself.

(2)
There are three forms of istisqa (prayer for rain):
➊ To formally go out to an open field, perform the prayer, and then supplicate in a specific manner.
➋ To supplicate to Allah Almighty for rain after any prayer.
➌ To raise the hands and supplicate for rain during the khutbah upon someone's request.
Imam Bukhari rahimahullah has mentioned this last form here.
Its detailed discussion will come in the Book of Istisqa.

(3)
In this hadith, an important miracle of the Messenger of Allah sallallahu alayhi wa sallam is mentioned: that Allah Almighty made the clouds subject to his command.
And Allah knows best.

1528. Commentary: "The whiteness of the armpits"—some people have thought that perhaps there was no hair in your (the Prophet's) armpits, but this notion is incorrect and without any evidence. Attempting to declare you free from human characteristics is not an act of wisdom, nor is such a thing a cause of virtue. The Messenger of Allah (sallallahu alayhi wa sallam) was a complete human being.