Abu Darda (may Allah be pleased with him) narrates: I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: "When a servant sends a curse upon something, the curse rises towards the sky, but before it reaches, the gates of the sky are closed. Then it descends towards the earth, and its gates are also closed. Then it turns to the right and to the left, and when it finds no way, it returns to the one upon whom the curse was sent, provided he is deserving of it; otherwise, it returns to the one who uttered it." Its chain is weak. Narrated by Abu Dawood.