Adam Clarke on Revelation 2:9

I know thy works - As he had spoken to the preceding Church, so he speaks to this: I know all that ye have done, and all that ye have suffered. The tribulation here mentioned must mean persecution, either from the Jews, the heathens, or from the heretics, who, because of their flesh-pampering doctrines might have had many partisans at Smyrna.

And poverty - Stripped probably of all their temporal possessions, because of their attachment to the Gospel.

But thou art rich - Rich in faith, and heir of the kingdom of Christ.

The blasphemy of them which say they are Jews - There were persons there who professed Judaism, and had a synagogue in the place, and professed to worship the true God; but they had no genuine religion, and they served the devil rather than God. They applied a sacred name to an unholy thing: and this is one meaning of the word blasphemy in this book.