Musannaf Ibn Abi Shayba 19:227

Abu Bakr narrated to us, he said: Waki’ narrated to us, from ‘Imran bin Hudayr, from Abu Mijlaz, who said: The trial (coercion) in the description is that he is threatened and [people] are gathered against him. If you strike him even a single lash, then his confession is of no value.