^2:10 Do not be afraid of what you are about to suffer. I tell you, the devil will put some of you in prison to test you, and you will suffer persecution for ten days. Be faithful, even to the point of death, and I will give you life as your victor’s crown.

Do not be afraid of what you are about to suffer.

On the human physical level, the Christian is expected to suffer for their beliefs (1 Peter 1:3-9). Suffering purifies and reveals the true metal of the believer. If that suffering includes death, a special martyr's grace is given at that time.

I tell you, the devil will put some of you in PRISON to test you, and

It is a mystery that the One with all power and control PERMITS the devil to test some Christians in this way. It is as though God gives the devil his best shot at trying to bring us down.

you will suffer persecution for ten days.

It is interesting that tribulation usually brings about the spread of the Gospel. That is, when Christians suffer trials, they move to get away. Yet God uses them in their new location to witness for Him.

It is not clear what is the signifigance of the ten days. It may be equated to the 10 periods of tribulation or 10 years of trials under Diocletian. Or it may be symbolic to mean a "short time", relatively speaking, to a God to whom time does not have much meaning because He is the great "I AM".

Daniel and his friends requested a different diet than the king's choice food. They wanted vegetables and water as their diet. So a test was run for 10 days to see what effect Daniel's diet would have on him and his friends. The results can be found in Daniel 1:8-16. The testing of the members of the Smyrna church may be a test similar to Daniel's.

Be faithful, even to the point of death, and I will give you life as your victor’s crown.

What a glorious promise....but we need these crowns to be able to cast them at His feet (Revelation 4:10). Earlier, the members of the church at Philadelphia were told to hold on to what they have so they would not lose their crown (Revelation 3:11). The crown is just one of the rewards (1 Corinthians 3:12-17) the Christian will receive. See Revelation 2:13 for one, Antipas, who received this crown.