Narrated Ibn Abbas (may Allah be pleased with them) that the Prophet Muhammad (peace be upon him) said: "Whoever describes a dream which he did not see (i.e., lies), he will be made to tie two grains of barley together on the Day of Resurrection, but he will not be able to do so. And whoever listens to the conversation of people who dislike him listening and move away from him, molten lead will be poured into his ears on the Day of Resurrection. And whoever makes a picture, he will be punished and will be asked to put a soul into it, but he will not be able to do so."
Narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "The greatest lie is that a person claims to have seen something with his eyes (i.e., a dream) which he has not seen."