Tertullian The Prescription Against Heretics soever He is the Son, of what substance soever He is man and God, of what faith soever He is the, teacher, of what reward soever He is the Promiser, did, whilst He lived on earth, Himself declare what He was, what He had been, what the Father's will was which He was administering, what the duty of man was which He was prescribing; either openly to the people, or privately to His disciples, of whom He had chosen the twelve chief ones to be at His side,[202] keeping them, as He did, inseparable (from Himself) in their attendance, in their discipleship, in their society, to whom, "when they were alone, He used to expound" all things[223] Clementine Homily XIX And Peter said: "We remember that our Lord and Teacher, commanding us, said, `Keep the mysteries for me and the sons of my house.' Wherefore also He explained to His disciples privately the mysteries of the kingdom of heaven.[57]