Examine yourselves, whether ye be in the faith; prove your own selves. Know ye not your own selves, how that Jesus Christ is in you, except ye be reprobates?
Examine - Greek, 'Try yourselves.'
Prove your own selves. This should be your first aim, rather than seeking "a proof of Christ speaking in me" (2 Corinthians 13:3).
Your own selves. If ye try your own selves ye will see that Christ is in you (Romans 8:10). Finding Christ in yourselves, by faith, ye may believe that He 'speaks in me' (2 Corinthians 13:3), by whose ministry ye have received this faith. Compare "we ... in Him" (2 Corinthians 13:4). To doubt it would be the sin of Israel, who, after so many experimental proofs of God's presence, still cried (Exodus 17:7). "Is the Lord among us or not?" (cf. Mark 8:11.)
Except ye be reprobates. The Greek softens it, 'somewhat reprobates' х adokimoi (G96)] - i:e., not abiding the "proof" (alluding to the same word in the context). Image from metals (Jeremiah 6:30; Daniel 5:27; Romans 1:28).