What is the source of the phrase "He who is silent about the truth is a mute devil," and is it connected to the Prophet, peace and blessings be upon him, or his Companions, or does it have an Islamic origin? And what is the truth about which one who is silent becomes a devil?

The saying: "He who is silent about the truth is a mute devil" has been cited by more than one scholar in condemnation of silence regarding evil. Ibn Taymiyyah and Ibn al-Qayyim mentioned it, and al-Nawawi and al-Qushayri attributed it to al-Hasan ibn Ali al-Naysaburi and al-Daqqaq. Perhaps al-Daqqaq was the first to utter this phrase. The truth about which silence is impermissible is everything that came in the Book of Allah and the Sunnah of His Messenger regarding commands, prohibitions, and manners.