What is the definition of Ijma' (consensus) in Fiqh (Islamic jurisprudence)?

Ijma' (consensus) is the agreement of all mujtahid (independent jurist) scholars from the Ummah of Muhammad, peace be upon him, after his death, in any era, on a religious matter. This excludes the agreement of non-mujtahids or the agreement of some mujtahids without others.

Ijma' is a proof according to the majority of scholars, and it is divided into two types: 1. Verbal and active Ijma': This is when every individual explicitly states their opinion or acts upon a ruling, and there is no disagreement regarding its validity as a proof. 2. Silent Ijma': This occurs when a statement or action originates from some scholars, and the remaining scholars remain silent. Its status as a proof or Ijma' is debated among scholars.

The majority of scholars hold that Ijma' is established from the moment it occurs, and the passing of the era of those who reached the consensus is not a condition. Therefore, no one is permitted to retract their opinion once it has conformed to the Ijma'.