They also have a complete knowledge of God's will. They are in possession of all knowledge brought by the angels to the prophets ("nabi") and the messengers ("rasul"). Their knowledge encompasses the totality of all times. They thus act without fault in religious matters. Shias regard Ali as the successor of Muhammad not only ruling over the community in justice, but also interpreting Islamic practices and its esoteric meaning. Hence he was regarded as being free from error and sin (infallible), and appointed by God by divine decree ("nass") to be the first Imam. Ali is known as "perfect man" ("al-insan al-kamil") similar to Muhammad, according to Shia viewpoint.