Obedience will prove the truth of Jesus' teachings
Scripture reference
John 7:17 (ASV)
17If any man willeth to do his will, he shall know of the teaching, whether it is of God, or whether I speak from myself.
Stories
George Müller, challenged to prove the truth of the Scriptures by obedience to them, was baptized as an adult, and after being a pastor for some time.