Narration of Ubayy ibn Kaʿb al-Anṣārī
Abu al-Qāsim al-Ṭabarānī said:
Abu Zurʿah al-Dimashqī narrated to us; Muḥammad ibn al-Ṣalt narrated to us; ʿAbd al-Ghaffār ibn al-Qāsim narrated to us, from ʿAdī ibn Thābit, from Zir ibn Ḥubaysh, from Ubayy ibn Kaʿb:
The Messenger of Allah ﷺ mentioned the Pool. They asked, “O Messenger of Allah, what is the Pool?” He replied:
“Its water is whiter than milk, colder than snow, sweeter than honey, and more fragrant than musk. Whoever drinks from it a single draught will never thirst again, while whoever is turned away from it will never be quenched.”

Abu Bakr ibn Abī ʿĀṣim also recorded it in his book al-Sunnah, saying: “‘Uqbah ibn Mukram narrated to us; Yūnus ibn Bukayr narrated to us; ʿAbd al-Ghaffār ibn al-Qāsim narrated to us…,” and he cited the same chain with similar wording. His version reads:
It was asked, “O Messenger of Allah, what is the Pool?” He said:
“By Him in Whose hand is my soul, its drink is whiter than milk, sweeter than honey, colder than snow, and more fragrant than musk; its vessels are more numerous than the stars. No one will drink from it and ever feel thirst again, and no one will be turned away from it and thereafter be satisfied.”

None of the compilers of the canonical collections, nor Imam Aḥmad, have included this ḥadīth. ⦗1⦘

Narration of Anas ibn Mālik al-Anṣārī, the servant of the Messenger of Allah ﷺ (may Allah be pleased with him)
Al-Bukhārī said:
Saʿīd ibn ʿUfayr narrated to us; Ibn Wahb narrated to us, from Yūnus. Ibn Shihāb said: Anas ibn Mālik related to me that the Messenger of Allah ﷺ said:
“The span of my Pool is like the distance between Aylah ⦗2⦘ and Ṣanʿāʾ in Yemen, and in it are pitchers as numerous as the stars in the sky.”
Muslim likewise related this ḥadīth, from Ḥarmalah, from Ibn Wahb, with the same chain. ⦗3⦘

(Another chain from Anas ibn Mālik, may Allah be pleased with him)
Al-Bukhārī said:
Muslim ibn Ibrāhīm narrated to us; Wahīb narrated to us; ʿAbd al-ʿAzīz narrated to us, from Anas, from the Prophet ﷺ, who said:
“Groups of my companions will indeed come to me at the Pool; but when I have recognized them, they will be pulled away from me ⦗4⦘. I will say, ‘My companions!’ and it will be said, ‘You do not know what they introduced after you.’”

Muslim also narrated it, from Muḥammad ibn Ḥātim, from ʿAffān, from Wahīb ibn Khālid, from ʿAbd al-ʿAzīz ibn Ṣuḥayb, with this wording. ⦗5⦘