The Severe Letter or Letter of Tears was a letter written to the Corinthians by the Apostle Paul. It is mentioned in 2 Corinthians 2:3-4 and again in 2 Corinthians 7:8:
For out of much affliction and anguish of heart I wrote unto you with many tears, not that ye should be grieved, but that ye might know the love which I have more abundantly for you.
— 2 Corinthians 2:4. [1]
The description does not match First Corinthians, so there are two main theories on the Severe Letter:
For more discussion on reconstructing Paul's correspondence with the Corinthians, see Second Epistle to the Corinthians.