`Abdullah b. `Amr al-`As, reported Allah's Messenger (ﷺ) 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 around 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 (ﷺ) said: I would be on the Cistern 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 Ummah, 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: lbn 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.