Cite it!
It's been cited time and time again...
Eph 1:13 In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that Holy Spirit of promise,
Eph 4:30 And grieve not the Holy Spirit of God, whereby ye are sealed unto the day of redemption.
It's a done deal...Signed, sealed and delivered...