Sayyiduna Uqbah bin Amir (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Whoever hangs a seashell (for protection), may Allah not give him peace; and whoever hangs an amulet, may Allah not fulfil (his affair) for him."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14892