NRSV
The revelation of Jesus Christ, which God gave him
to show his servants what must soon take place;
he made it known by sending his angel
to his servant John,
2 who testified to the word of God and to the testimony of Jesus Christ, even to all that he saw.

NJB:
A revelation of Jesus Christ, which God gave him
so that he could tell his servants what is now to take place very soon;
he sent his angel to make it known
to his servant John,
2 and John has borne witness to the Word of God and to the witness of Jesus Christ, everything that he saw.

RSV
The revelation of Jesus Christ, which God gave him
to show to his servants what must soon take place;
and he made it known by sending his angel
to his servant John,
2 who bore witness to the word of God and to the testimony of Jesus Christ, even to all that he saw.

NIV
The revelation of Jesus Christ, which God gave him
to show his servants what must soon take place.
He made it known by sending his angel
to his servant John,
2 who testifies to everything he saw-- that is, the word of God and the testimony of Jesus Christ.