It is narrated from Hazrat Amr bin Aas (may Allah be pleased with him) that Muhammad bin Abi Bakr was brought as a captive. Amr began to ask him questions; he wished that he would seek protection from him. So he said that the Prophet (peace and blessings be upon him) said: Even the lowest-ranking Muslim can grant protection to someone on behalf of all Muslims (and then his protection will be the responsibility of all Muslims).