Jesus told his disciples to take the log out of their own eye before they tried to take a splinter out of their neighbor's eye. If we do the work to purify our own vision in love and joy, St. Paul assures us that this labor will not be in vain.
Based on Luke 6:39–45:
Jesus told his disciples a parable: ‘Can a blind person guide a blind person? Will not both fall into a pit? A disciple is not above the teacher, but everyone who is fully qualified will be like the teacher. Why do you see the speck in your neighbour’s eye, but do not notice the log in your own eye? Or how can you say to your neighbour, “Friend, let me take out the speck in your eye”, when you yourself do not see the log in your own eye? You hypocrite, first take the log out of your own eye, and then you will see clearly to take the speck out of your neighbour’s eye.
‘No good tree bears bad fruit, nor again does a bad tree bear good fruit; for each tree is known by its own fruit. Figs are not gathered from thorns, nor are grapes picked from a bramble bush. The good person out of the good treasure of the heart produces good, and the evil person out of evil treasure produces evil; for it is out of the abundance of the heart that the mouth speaks.
(New Revised Standard Version Bible: Anglicized Edition, copyright © 1989, 1995 National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved worldwide. http://nrsvbibles.org)