Salim bin Hanzalah said that we went to Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him) to have a conversation. When he stood up, we also stood up and began to walk behind him. Then Sayyiduna Umar (may Allah be pleased with him) came close to us and, going behind Ubayy (may Allah be pleased with him), struck him with a whip. The narrator said: He stopped it with his wrist and said: O Commander of the Faithful! What are you doing? He replied: Do you not see (this following behind)? It is a trial for the one who is followed and humiliation and disgrace for the one who follows.