Introduction to 2 Timothy

The first design of this epistle seems to have been, to apprize Timothy of what had occurred during the imprisonment of the apostle, and to request him to come to Rome. But being uncertain whether he should be suffered to live to see him, Paul gives a variety of advices and encouragements, for the faithful discharge of his ministerial duties. As this was a private epistle written to St. Paul's most intimate friend, under the miseries of imprisonment, and in the near prospect of death, it shows the temper and character of the apostle, and contains convincing proofs that he sincerely believed the doctrines he preached.

-- taken from Matthew Henry's Concise Commentary