so that you may know the certainty of the things you have been taught.

Proverbs 22:21
to show you true and reliable words, that you may soundly answer those who sent you?

Acts 18:25
He had been instructed in the way of the Lord and was fervent in spirit. He spoke and taught accurately about Jesus, though he knew only the baptism of John.

Romans 2:18
if you know His will and approve of what is superior because you are instructed by the law;

1 Corinthians 14:19
But in the church, I would rather speak five coherent words to instruct others than ten thousand words in a tongue.

Galatians 6:6
Nevertheless, the one who receives instruction in the word must share in all good things with his instructor.

That you might know the certainty of those things, wherein you have been instructed.