A.T. Robertson Commentary Luke 23:51

"(he had not consented to their counsel and deed), [a man] of Arimathaea, a city of the Jews, who was looking for the kingdom of God:" — Luke 23:51 (ASV)

He had not consented to their counsel and deed (ουτος ουκ ην συνκατατεθειμενος τη βουλη κα τη πραξε αυτων). This parenthesis is given by Luke alone and explains that, though a councillor (βουλευτης, Mr 5:43) he had not agreed to the vote of the Sanhedrin. It is fairly certain that both Joseph and Nicodemus were suspected of sympathy with Jesus and so were not invited to the trial of Jesus.

Was looking for (προσεδεχετο). Imperfect middle. Mr 15:43 has the periphrastic imperfect (ην προσδεχομενος).