Musnad Ahmad

It is narrated from Hazrat Ubaid (may Allah be pleased with him) that during the Prophetic era, two women were fasting. A man came and said, "O Messenger of Allah! There are two women here who are fasting, but due to thirst they are near death." The Noble Prophet (peace and blessings be upon him) heard this and remained silent or turned away. He came again at midday and said, "O Prophet of Allah! By Allah, they will die." The Noble Prophet (peace and blessings be upon him) said, "Bring them here." When both of them came, a bowl was called for. The Noble Prophet (peace and blessings be upon him) said to one of them, "Vomit into it." She vomited, and blood, pus, and pieces of flesh came out until half the bowl was filled. Then he said the same to the other, and she also vomited the same things until the bowl was full. The Noble Prophet (peace and blessings be upon him) said, "They abstained from what Allah made lawful and kept the fast, but by indulging in what Allah made unlawful, they broke the fast. Both of them were sitting together eating the flesh of people (i.e., backbiting)."