It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) saw some camels, some of which had bells tied on them. When he (peace and blessings be upon him) heard their sound, he said: "What is this?" A man said: A jaljal (a small bell). the Messenger of Allah (peace and blessings be upon him) said: "And what is a jaljal?" He said: A bell. He (peace and blessings be upon him) said: "Yes; go and cut it off and throw it away." He did so, then the man came back and said: O Messenger of Allah! What is wrong with it? the Messenger of Allah (peace and blessings be upon him) said: "The angels do not accompany a caravan in which there is a bell."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20303