The Second Letter to Timothy is one of the three pastoral letters included in the New Testament, written by Paul of Tarsus.

Since the eighteenth century it has been customary to group together, under the name of pastoral letters, the First Letter to Timothy, the Second Letter to Timothy and the Letter to Titus: in these letters Paul addresses his closest collaborators Timothy and Titus, to whom he entrusted the task of following the various churches he founded.

(From Italian Wikipedia)