Bukhari

Hadith Commentary:
From here, the relevance of the chapter is derived.
Because the Messenger of Allah (sallallahu alayhi wa sallam) did not object to the person with the cistern regarding the fact that he drives animals away from his cistern.

Hadith Commentary:
The Messenger of Allah (sallallahu alayhi wa sallam) did not object to the owner of the cistern who would drive away strange camels from his cistern.
If he were not more entitled to the water of his cistern, how could he take such an action? Furthermore, in this hadith, the cistern is attributed to the Messenger of Allah (sallallahu alayhi wa sallam), and he is more entitled to give drink to his own and to drive others away.
On the Day of Resurrection, he will exercise the authority granted to him by Allah.
(Fath al-Bari: 5/55)

Hadith Commentary:
In this hadith, regarding those people about whom it has been reported that they will be prevented from reaching the Prophet Muhammad (sallallahu alayhi wa sallam) at the Pond of Kawthar, it is difficult to specify exactly who these people will be and to which group they will belong. It is not necessary for us to determine this.

For us, the real lesson is that if we desire to meet the Messenger of Allah (sallallahu alayhi wa sallam) at the Pond of Kawthar, then we must firmly adhere to the religion that the Messenger of Allah (sallallahu alayhi wa sallam) brought for us, and we should not introduce any alteration or addition or subtraction from our own side, because the Messenger of Allah (sallallahu alayhi wa sallam) has placed great hopes in the righteous individuals of this ummah, as he said:

“In the Hereafter, every prophet will have a pond, and they will take pride among themselves over which of them has more people coming to drink from it. I hope that among all of them, the number of people coming to me will be the greatest.” (Jami‘ at-Tirmidhi, Description of the Day of Judgment, Hadith: 2443)

Hadith Commentary:
(1)
By "my companions" (ashabi) in the narration are meant those people who became apostates after the death of the Messenger of Allah (sallallahu alayhi wa sallam), against whom Abu Bakr as-Siddiq (radi Allahu anhu) waged jihad.
Or, it may refer to those so-called Muslims who came later and invented new innovations (bid‘ah) in the religion, thereby distorting its appearance, because the noble Companions (radi Allahu anhum) were far removed from innovation.

(2)
Those who hold gatherings for the Prophet’s birthday (mawlid), the customary third-day, fateha, seventh, eleventh, fortieth, recitation gatherings for the deceased (qal khwani), grave worshippers, those who hold festivals (urs) at graves, those who build shrines over the graves of saints and give them the status of mosques, deceitful types of spiritual guides (pir o murshid) and self-appointed imams—all of these are included in the meaning of this hadith.
Outwardly, they appear to be Muslims, but inwardly they are completely immersed in disbelief, polytheism, innovations, and rituals.
Allah, the Exalted, will not grant such people of innovation (ahl al-bid‘ah) the drink from the blessed hand of the Messenger of Allah (sallallahu alayhi wa sallam) at the Pond of Kawthar.

(3)
It is necessary for a sincere Muslim to avoid prevalent innovations (muruwwajah bid‘at) in every circumstance, so that he may be granted the water of the Pond of Kawthar.
The Messenger of Allah (sallallahu alayhi wa sallam) said:
“On my Pond of Kawthar, the majority (from among the Companions) will be the poor Emigrants (fuqara muhajirin), disheveled in hair and with dirty, soiled clothes. These are the people who neither married women of luxury and comfort, nor were doors opened for them.”
(Musnad Ahmad: 2/132, 5/275, and Silsilat al-Ahadith as-Sahihah by al-Albani, Hadith: 1082)

Hadith Commentary: Benefits and Issues: Those people who will not be deserving of drinking from your cistern, you will remove them for the sake of giving water to your ummah, so that your ummah may drink water with ease.