The words "in chains" are a metonym for being in prison. Alternate translation: "I am now in prison because I am a representative of the gospel" (See: [[rc://en/ta/man/jit/figs-metonymy]])
The word "pray" is understood from verse 19. Alternate translation: "so pray that whenever I teach the gospel, I will speak it as boldly as I should" or "pray that I may speak the gospel as boldly as I should" (See: [[rc://en/ta/man/jit/figs-explicit]])