Bukhari

Hadith Commentary:
(1)
The command of Allah, the Exalted, is:
“We have granted you al-Kawthar.”
(al-Kawthar: 1/108)
This Kawthar has various meanings and aspects:
The word Kawthar contains an intensive form (mubalagha).
The linguists have defined it as:
Abundant good.

(2)
It is established from many ahadith that Kawthar is the name of a river in Paradise which was granted to you (sallallahu alayhi wa sallam). Thus, in the hadith regarding the incident of Mi’raj, the Messenger of Allah (sallallahu alayhi wa sallam) stated:
“I reached a river whose banks had domes of hollow pearls.
I asked Jibril:
What is this river? He replied:
This is Kawthar which Allah, the Exalted, has granted to you.”
(Sahih al-Bukhari, al-Tafsir, Hadith: 4964, 4966)
In addition, by Kawthar is also meant the Hawd al-Kawthar (the Pond of Kawthar) which will be granted to you on the Day of Standing in the Plain of Resurrection, the day when all people will be overwhelmed and exhausted by thirst, and will be crying out al-atash al-atash, meaning “thirst, thirst.”

(3)
This abundant good is related to the Hereafter.
In this world as well, you (sallallahu alayhi wa sallam) were granted abundant good.
You were given prophethood and the great blessing of the Magnificent Qur’an, which transformed a savage nation within the short span of 23 years.
You (sallallahu alayhi wa sallam) left behind a group of noble Companions (radi Allahu anhum) who, in a short time, prevailed over the entire world.
In any case, this is also part of the abundant good: that you saw your mission fully succeed during your lifetime.