What is the significance of the message “every case must be established by the testimony of two or three witnesses” in 2 Corinthians 13:1? In 2 Corinthians, Paul mentioned that it was the third time he was going to visit the people there, and he added that &quot;As the scriptures say, the facts of every case must be established by the testimony of two or three witnesses&quot;.

2 Corinthians 13:1-2 (NLT)
1 This is the third time I am coming to visit you (and as the Scriptures say, “The facts of every case must be established by the testimony of two or three witnesses”). 2 I have already warned those who had been sinning when I was there on my second visit. Now I again warn them and all others, just as I did before, that next time I will not spare them.

I was trying to understand what Paul is trying to say when he mentioned “The facts of every case must be established by the testimony of two or three witnesses” in 2 Corinthians 13:1.
What is the significance of the message “The facts of every case must be established by the testimony of two or three witnesses” ?
Since Paul was coming to deal with a sinning church member, he is back referencing Jesus' command on dealing with sins in the church in Matthew 18:


  But if he does not listen to you, take one or two more with you, so that BY THE MOUTH OF TWO OR THREE WITNESSES EVERY FACT MAY BE CONFIRMED.


Which is itself a reference to Deuteronomy 19:15:


  A single witness shall not rise up against a man on account of any iniquity or any sin which he has committed; on the evidence of two or three witnesses a matter shall be confirmed.


Paul is reiterating that while he "knows" there is sin in the church, even as an Apostle of Jesus, he won't cast a man out on hearsay: it must be confirmed in the proper process.