Jami` at-Tirmidhi Book 47, Hadith 414
“Umar used to ask me questions in front of the Companions of the Prophet. So Abdur-Rahman bin Awf said to him: ‘Why do you ask him, while we have children like him?’” He said: “Umar said to him: ‘It is because of what you know (about him).’ So he asked him about this Ayah: ‘When there comes the help of Allah and the Conquest.’ I said: “It is only regarding the (end of the) life span of the Messenger of Allah, informing him of it.” Then he recited the Surat until its end. So Umar said to him: “By Allah! I know not about it, but what you know.”
the Messenger of Allah said: “Al-Kauthar is a river in Paradise, whose banks are of gold, and it flows over pearls and corundum. Its dirt is purer than musk, and its water is sweeter than honey and whiter than milk.”
“One day the Messenger of Allah ascended As-Safa and called out: ‘O people! Come at once!’ So the Quraish gathered before him. He said: ‘I am a warner for you before the coming of a severe punishment. Do you think that if I informed you that the enemy was preparing to attack you in the evening or in the morning, would you believe me?’ So Abu Lahab said: ‘Is it for this that you gathered us? May you perish?’ So Allah, Blessed is He and Most High, revealed: Perish the hands of Abu Lahad, perish he.”