Sahih Bukhari

Narrated `Abdullah bin `Umar:While `Umar was at home in a state of fear, there came Al-`As bin Wail As-Sahmi Abu `Amr, wearing an embroidered cloak and a shirt having silk hems. He was from the tribe of Bani Sahm who were our allies during the pre-Islamic period of ignorance. Al-`As said to `Umar ""What is wrong with you?"" He said, ""Your people claim that they would kill me if I become a Muslim."" Al-`As said, ""Nobody will harm you after I have given protection to you."" So Al-`As went out and met the people streaming in the whole valley. He said, ""Where are you going?"" They said, ""We want Ibn Al-Khattab who has embraced Islam."" Al-`As said, ""There is no way for anybody to touch him."" So the people retreated