The Messenger of Allah ﷺ said, "I have been granted al-Kawthar. It is a flowing river, not one carved out by digging. Its two banks are domes of pearls. I struck my hand into its soil and found it to be fragrant musk, and its pebbles were pearls."
في قوله تعالى: {إنا أعطيناك الكوثر} [سورة الكوثر: ١]
فقال رسول الله ﷺ: أعطيت الكوثر، فإذا هو نهر يجري، ولم يشق شقا، فإذا حافتاه قباب اللؤلؤ، فضربت بيدي إلى تربته فإذا مسكة ذفرة، وإذا حصاه اللؤلؤ.
Imam Ahmad (13578) and Abu Yaala (3529) both narrated it from the hadith of Affan bin Muslim, who said, Hammad narrated to us, Thabit informed us, from Anas, and he related it. Ibn Hibban also narrated it in his Sahih (6471) through the route of Hammad bin Salama, in similar fashion.