Bukhari

Hadith Commentary:
In this hadith, it is mentioned that the Noble Messenger (sallallahu alayhi wa sallam) went to the marketplace.
It is thus established that going to the marketplace when necessary is not objectionable; however, it is essential to uphold trustworthiness and honesty at every step there.

Hadith Commentary:
The relevance of this hadith to the chapter is that it mentions the Prophet’s (sallallahu alayhi wa sallam) going to the marketplace, that is, to Baqi‘.
Some have said that in that era, a marketplace would also be set up in Baqi‘.
As for the ruling regarding the use of a kunya, this was applicable only during his blessed lifetime.
As is the statement of Imam Malik (rahimahullah).

Hadith Commentary:
(1)
Imam Bukhari rahimahullah has narrated the hadith from Anas radi Allahu anhu through two routes, by which he intends to indicate that in the first narration, the "market" (sūq) refers to the market of Baqi‘. This is also supported by a hadith in Musnad Ahmad. The narrator states that the Messenger of Allah sallallahu alayhi wa sallam came to us in Baqi‘ and said:
“O group of traders! While buying and selling, a person becomes involved in false oaths and deception, etc., so cleanse such slips with charity and the like.” (Musnad Ahmad: 6/4)
It is possible that in the blessed era of the Messenger of Allah sallallahu alayhi wa sallam, a market would be set up there.

(2)
From this hadith, it is established that the Messenger of Allah sallallahu alayhi wa sallam would go to the market; therefore, going to the market when needed is not blameworthy, but it is extremely necessary to uphold trustworthiness and honesty at every step there. The disbelievers used to object to the Messenger of Allah sallallahu alayhi wa sallam, saying that this Messenger eats food and goes to the market, as if, in their view, going to the market was contrary to the rank of prophethood. From this, it is proven that his going to the market is not against the dignity of messengership or the office of leadership (imamate). The Noble Qur’an has also answered this objection. ()

Hadith Commentary: Benefits and Issues:
From this hadith, it is understood that the Prophet (sallallahu alayhi wa sallam) forbade adopting his kunyah (patronymic) because it caused confusion.
When one man called another by the kunyah "Abu al-Qasim," the Prophet (sallallahu alayhi wa sallam) thought he was being called, so he turned his attention.
When that man clarified that he had not called the Prophet (sallallahu alayhi wa sallam), then the Prophet (sallallahu alayhi wa sallam) said:
"You may take my name, but do not take my kunyah."
From this, it is also understood that the Arabs generally used to address others by their kunyah, especially respected and honored individuals, and did not call them by their given names.
Therefore, in the case of adopting the name, the possibility of confusion was less, and there is another reason for this, which will be mentioned ahead.
For this reason, there are different opinions among the scholars regarding adopting the kunyah "Abu al-Qasim":
(1) Imam Malik, the majority of the Salaf, and the majority of jurists and scholars hold the view that this prohibition was specific to the time of the Messenger of Allah (sallallahu alayhi wa sallam), when there was a risk of confusion due to adopting this kunyah. Now, since there is no longer any fear of confusion, anyone may adopt this kunyah, whether his name is Muhammad or Ahmad or not.
(2) Imam al-Shafi'i and the Zahiri scholars are of the opinion that adopting the kunyah "Abu al-Qasim" is not permissible for anyone, whether his name is Muhammad or Ahmad or not.
(3) According to Imam Ibn Jarir, this text is for tanzeeh (discouragement) or out of etiquette and respect.
(4) Adopting this kunyah is prohibited for the person whose name is Muhammad or Ahmad, and for one whose name is not so, there is no harm in adopting the kunyah "Abu al-Qasim." This is the position of some of the early scholars.
(5) Adopting the kunyah "Abu al-Qasim" is prohibited for everyone, and likewise, naming someone "Qasim" is not permissible, so that his father may not be called "Abu al-Qasim."

Explanation:
1:
There is a difference of opinion among the scholars regarding this matter.
Some say that during the lifetime of the Prophet (sallallahu alayhi wa sallam), this was prohibited,
but after him, it is permissible to take his name and his kunyah (patronymic).
Some say that it is prohibited to combine both together,
while others say that the prohibition pertains only to the kunyah.
The first opinion is the most correct.
(See the next two hadiths)

Benefits and Issues:
➊
Baqi‘ was a field near Madinah Munawwarah, a part of which was a graveyard, while the rest of the field was used for buying and selling. Nowadays, this field is the cemetery of the people of Madinah, which is commonly known as "Jannat al-Baqi‘." In one narration of this incident, these words appear: "The Prophet (sallallahu alayhi wa sallam) was in the marketplace when a man said: O Abu al-Qasim! ..." (Sahih al-Bukhari, al-Manaqib, Chapter: The Kunya of the Prophet (sallallahu alayhi wa sallam), Hadith: 3537)

➋
By "kunya" is meant the name that is given in relation to one's children, with "Abu" (father of) or "Umm" (mother of), for example: Abu Bakr (radi Allahu anhu) and Umm ‘Abdullah (A’ishah Siddiqah radi Allahu anha).

➌
There are different opinions on this issue:
The title that Imam Ibn Majah (rahimahullah) has written for the chapter indicates that his view is that a person whose name is Muhammad should not take the kunya "Abu al-Qasim." Another person may take this kunya. Some scholars are of the opinion that this prohibition was only during the lifetime of the Prophet (sallallahu alayhi wa sallam), as is also apparently understood from the hadith under discussion.