Here, with these few words, St. Paul encourages his son Timothy to take courage, to endure hardship, to keep doing what God has called him to do.
For even though Paul himself is in chains and bound, God’s Word is not bound.
For as the rain comes down, and the snow from heaven, And do not return there, But water the earth, And make it bring forth and bud, That it may give seed to the sower And bread to the eater, So shall My word be that goes forth from My mouth; It shall not return to Me void, But it shall accomplish what I please, And it shall prosper in the thing for which I sent it (Isaiah 55:10-11)
Man shall not live by bread alone; but man lives by every word that proceeds from the mouth of the LORD (Deuteronomy 8:3; Matthew 4:4; Luke 4:4)
In his first letter to Timothy, Paul had told Timothy to Remain in Ephesus, that he commandsome that they teach no other doctrine.