Abdullah ibn Umar
According to the narration of Muhammad Hanafiyyah, many companions met with Ali and wanted to pledge allegiance to him. At first, Ali objected, but later said that any allegiance should be in public and in the mosque. Kufi narrations state that Malik al-Ashtar was the first to pledge allegiance to him. It seems that Ali personally did not force others to pledge allegiance to him. Thus, people such as Sa'ad ibn Abi Waqqas, Abdullah ibn Umar and Usama ibn Zayd refused to pledge allegiance to Ali.