Sahih Muslim Book 30, Hadith Number 5711.

Chapter : The cistern of our Apostle (may peace be upon him) and its characteristics.

Jabir b. Samura reported Allah’s Messenger (may peace be upon him) as saying: Behold, I shall be present ahead of you on the Cistern, and the distance between its different sides would be like that between Sana’ and Aila, and its jugs would be like stars in the sky.