Don’t be afraid of what you are about to suffer. The devil will throw some of you into prison to test you. You will suffer for ten days. But if you remain faithful even when facing death, I will give you the crown of life. Revelation 2:10 NLT
The phrase “Do not be afraid” is in the Bible at least 77 times. Jesus is encouraging them to stay faithful – He is the first and last and was dead and now alive. He will be with them even unto death. He has overcome death and they will also rise again.
Many scholars say the ten days represent a short period when the persecution would be at its worst. In prophecy, a day stands for a year. See Ezekiel 4:6 and Numbers 14:34.
Under emperor Diocletian from 303 to 313 AD, the church of Smyrna experienced extreme persecution. The persecution came to an end when Constantine became emperor.