Come up here, and I will show you things which must take place after this

Revelation 4
After these things I looked, and behold, a door standing open in heaven. And the first voice which I heard was like a trumpet speaking with me, saying, “Come up here, and I will show you things which must take place after this.”

God tells things to his friends, and his friends include humans. There have been a few people, whom we know well, whom God has regarded as His friends such as Abraham, Moses, David, etc. However we also see that God seems to be silent for a majority of people. So to whom does God would say, "come up here" or "I will show you things".

There have been various commandments of God, but one which is simple and non-legalistic that God repeatedly tells His people is to obey His statutes and commandments and not turn away from them. Basically He wants our obedience and we all know what are the things God told us already. We just need to obey, and that will bring us close to Him, and He will reveal even more to us - like the parable the more we are faithful, the more He will trust us in.

A word to be careful in temptation is that it leads us directly to the opposite direction. Instead of being a little faithful and being led higher by God, temptation tempts us with little things. When we sin a little, the next temptation will be greater and leads us to the next level further away from God.