by these

Luke 16:29-31
But Abraham replied, 'They have Moses and the prophets; let your brothers listen to them.' . . .

John 5:39
You pore over the Scriptures because you presume that by them you possess eternal life. These are the very words that testify about Me,

John 20:31
But these are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in His name.

John 21:25
There are many more things that Jesus did. If all of them were written down, I suppose that not even the world itself would have space for the books that would be written.

2 Peter 1:19-21
We also have the message of the prophets, which has been confirmed beyond doubt. And you will do well to pay attention to this message, as to a lamp shining in a dark place, until the day dawns and the morning star rises in your hearts. . . .

study

Ecclesiastes 1:18
For with much wisdom comes much sorrow, and as knowledge grows, grief increases.