Bukhari

Hadith Commentary:
The author of Tafheem al-Bukhari, a Hanafi Deobandi, says that the meaning is that the method of the Friday (Jumu‘ah) call to prayer (adhan) was different from the five daily prayers’ adhan.
And in both cases, the adhan was given a little before the prayer.
But with the Friday adhan, the sermon (khutbah) would begin immediately, and after that, the prayer would be started right away.
It should be remembered that nowadays, when the sermon of Jumu‘ah begins, the mu’adhdhin gives the adhan softly in front of the imam.
This is against the Sunnah.
The adhan for the sermon should also be given from an elevated place and in a loud voice.
Ibn Munir says that Imam al-Bukhari rahimahullah, through this hadith, refuted the people of Kufa who say that sitting on the pulpit (minbar) before the sermon is not legislated.

Hadith Commentary:
(1)
According to some scholars of Kufa, it is not legislated for the preacher to sit on the pulpit at the time of the call to prayer (adhan), whereas Imam Malik, Shafi'i, and the majority of jurists (rahimahumullah) have considered it a Sunnah. Imam Bukhari rahimahullah has also established this chapter heading in support of these scholars. (Fath al-Bari: 2/510)

(2)
There is a difference of opinion as to whether sitting on the pulpit at the time of the adhan is for the purpose of rest, or in order to listen to the adhan with calmness and tranquility. Those who consider it to be for rest hold that there is no difference between Friday and the two Eids, while those who consider this sitting to be for listening to the adhan say that sitting is legislated for Friday, but not for the two Eids, because there is no adhan on those occasions.

(3)
Allamah 'Ayni rahimahullah has written that Imam Bukhari rahimahullah should have established the chapter heading in these words: "The statement regarding giving the adhan when the Imam sits on the pulpit," because this is what is established from the hadith. (Umdat al-Qari: 2/76) However, there is more weight in Imam Bukhari rahimahullah's chapter heading, as we have explained.