John 7:17

17 Anyone who chooses to do the will of God will find out whether my teaching comes from God or whether I speak on my own.

Read John 7:17 Using Other Translations

If any man will do his will, he shall know of the doctrine, whether it be of God, or whether I speak of myself.
If anyone's will is to do God's will, he will know whether the teaching is from God or whether I am speaking on my own authority.
Anyone who wants to do the will of God will know whether my teaching is from God or is merely my own.