Sayyiduna Abu Umamah al-Bahili (may Allah be pleased with him) says: I heard the Messenger of Allah (peace and blessings be upon him) say: "Once, while I was sleeping, two men came to me, took hold of me by my upper arms and brought me to a rugged mountain, and said to me: 'Climb it.' I said: 'I am not able to climb it.' They said: 'We will make it easy for you.' So I climbed until, when I was on the mountain, I heard intense voices. I said: 'What are these voices?' They said: 'This is the howling of the people of Hell.' Then I was taken further until I came upon a people hung upside down, their mouths torn at the corners and blood flowing from them. I said: 'Who are these people?' They said: 'These are the ones who broke their fast before it was lawful to break it.'"
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8006