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.

1 Thessalonians 4

4:15 For this we say unto you by the word of the Lord, that we which are alive and remain unto the coming of the Lord shall not prevent them which are asleep.