Analysis of information sources in references of the Wikipedia article "Muadh ibn Jabal" in English language version.
Muhammad himself praised the knowledge of Mu'adh. It was narrated from 'Anas ibn Malik (أنس بن مالك) that the Messenger of Allah said: 'The most knowledgeable of what is lawful [halāl] and unlawful [harām] is Mu'adh ibn Jalal.'