Matthew 16:16 And Simon Peter answered and said, Thou art the Christ, the Son of the living God. [kjv]
16:17 And Jesus answered and said unto him, Blessed art thou, Simon Bar–jona: for flesh and blood hath not revealed it unto thee, but my Father which is in heaven. [kjv]
16:18 And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it. [kjv]
16:19 And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven. [kjv]
16:20 Then charged he his disciples that they should tell no man that he was Jesus the Christ. [kjv]
The disciples are not tell anyone about this. How long does this "
secrecy" requirement extend? Modern "
secrecy" requirements in the military extend to the end of one's life. To insure that one does not violate this "
secrecy" requirement, most people will not talk about anything related to that "
secrecy".
Perhaps Jesus indicated to Matthew that he should write what was said but nothing more.