Sahih Muslim | Book 30 | Hadith Number 5684

Narrated by Abdullah b. 'Amr al-'As,
Abdullah b. 'Amr al-'As, reported Allah's Messenger (may peace be upon him) as saying: My Cistern (is as wide and broad that it requires) a month's journey (to go round it) all, and its sides are equal and its water is whiter than silver, and its odour is more fragrant than the fragrance of musk, and its jugs (placed round it) are like stars in the sky; and he who would drink from it would never feel thirsty after that. Asma', daughter of Abu Bakr said: Allah's Messenger (may peace be upon him) said: I would be on the Cistern and so that I would be seeing those who would be coming to me from you, but some people would be detained (before reaching me). I would say: My Lord, they are my followers

and belong to my Umma, and it would be said to me: Do you know what they did after you? By Allah, they did not do good after you, and they turned back upon their heels. He (the narrator) said: Ibn Abu Mulaika used to say (in supplication): O Allah, I seek refuge with Thee that we should turn back upon our heels or put to any trial about our religion.