Acts 7: Ver. 55. But he, being full of the Holy Ghost, looked up stedfastly into heaven, and saw the glory of God, and Jesus standing on the right hand of God.
As ready to revenge the injuries done to his proto-martyr. Christus stat ut Vindex, sedet ut Iudex. Christ stands as a defender, and sits as a judge.
The painting: Martyrdom of Saint Stephen by Pietro da Cortona.