A ---There so many Hadiths pertaining to this. Foremost among which are:

Narrated 'Uqbah Ibn 'Amir (May Allah be pleased with him): One day the Prophet (Peace be upon him) went out and offered the funeral prayers of the martyrs of Uhud and then went up the pulpit and said: "I will pave the way for you as your predecessor and will be a witness on you. By Allah! I see my Fount (Kauthar) just now and I have been given the keys of all the treasures of the earth (or the keys of the earth). By Allah! I am not afraid that you will worship others along with Allah after my death, but I am afraid that you will fight with one another for the worldly things.”(Sahih Bukhari)

Abu Hurairah (May Allah be pleased with him) reported: Verily Allah's Messenger (Peace be upon him) said: My Cistern has its dimensions wider than the distance between Aila (Jerusalem) and Aden, and its water is whiter than ice and sweeter than the honeydiluted with milk, and its cups are more numerous than the numbers of the stars. Verily I shall prevent the (faithless) people there from just as a man prevents the camels of the people from his fountain. They said: Messenger of Allah, will you recognize us on that day? He said: Yes, you will have distinctive marks which nobody among the peoples (except you) will have,' you would come to me with blazing forehead and bright hands and feet on account of the traces of ablution." (Sahih Bukhari)

Narrated Anas (May Allah be pleased with him): When the Prophet (Peace be upon him) was made to ascend to the heavens. He (Peace be upon him) said (after his return), "I came upon a river (in Paradise) the banks of which were made of tents of hollow pearls. I asked Jibril (Gabriel), 'What is this (river)?' He replied, "This is the Kauthar.” (Sahih Bukhari)