Āsim ibn Alī said: “I debated a follower of Jahm, and it became clear from his words that he did not believe there was a Lord in heaven.”

Alī ibn Āsim said: “Those who say that Allah has a son are no greater in disbelief than those who say that Allah does not speak.”

He also said: “Beware of al-Marīsī and his followers, for their discourse is the ABC of heresy. I spoke with their teacher, Jahm, and he did not affirm that there was a God in heaven.”

This is how I found this reported from him in al-Bukhārī’s Khalq al-Afʿāl (The Creation of Actions). The first report was transmitted by Ibn Abī Hātim from Āsim ibn Alī ibn Āsim in the book