He that hath received his testimony hath set to his seal that God is true.
Note 2 at Joh 3:33: The phrase "set to his seal" refers to the seals that government officials or noblemen would use to identify themselves. It is simply stating that those who receive the testimony of Jesus have identified themselves with God's truth. The New American Standard translation reads, "has set his seal to this." The Williams New Testament says, "has certified with a seal that God is true." Beck's American Translation says, "has stamped with his seal of approval that God tells the truth."