Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Uqbah bin Amir (may Allah be pleased with him) that a group came to the Prophet (peace and blessings of Allah be upon him) (to pledge allegiance). The Prophet (peace and blessings of Allah be upon him) accepted the pledge from nine (9) individuals and did not accept it from one. They said: O Messenger of Allah! You accepted the pledge from nine (9) individuals and left one (what is the reason)? The Prophet (peace and blessings of Allah be upon him) said: "He has hung an amulet." He put his hand in and cut off the amulet. Then the Prophet (peace and blessings of Allah be upon him) accepted his pledge and said: "Whoever hangs an amulet has committed shirk (associating partners with Allah)."