Vincent's NT Word Studies
8. He knew (hdei). Imperfect. He was all along aware.Thoughts (dialogismouv). See on Jas. ii. 4; Matt. xv. 19.
Robertson's NT Word Studies
6:8 {But he knew their thoughts} (autos de eidei tous dialogismous autwn). In Luke alone. Imperfect in sense, second past perfect in form eidei from oida. Jesus, in contrast to these spies (Plummer), read their intellectual processes like an open book. {His hand withered} (xeran ten ceira). Predicate position of the adjective. So in #Mr 3:3. {Stand forth} (steqi). Luke alone has this verb, second aorist active imperative. #Mr 3:3 has {Arise into the midst} (egeire eis to meson). Luke has {Arise and step forth into the midst} (egeire kai steqi eis to meson). Christ worked right out in the open where all could see. It was a moment of excitement when the man stepped forth (este) there before them all.