The Epistles of Paul the Apostle to the Thessalonians were written by Paul from Corinth about A.D. 52. These two letters are the earliest writings of the New Testament. Paul tells these Christians what sort of persons they must be, and that they must do their duty every day and not stand idle, waiting for the Second Coming.

2 Thessalonians 2

2:15 Therefore, brethren, stand fast, and hold the traditions which ye have been taught, whether by word, or our epistle.