Matthew 7:1-14 TNIV
“Do not judge, or you too will be judged. For in the same way you judge others, you will be judged, and with the measure you use, it will be measured to you.
“Why do you look at the speck of sawdust in someone else’s eye and pay no attention to the plank in your own eye? How can you say, ‘Let me take the speck out of your eye,’ when all the time there is a plank in your own eye? You hypocrite, first take the plank out of your own eye, and then you will see clearly to remove the speck from the other person’s eye.
“Do not give dogs what is sacred; do not throw your pearls to pigs. If you do, they may trample them under their feet, and then turn and tear you to pieces.
“Ask and it will be given to you; seek and you will find; knock and the door will be opened to you. For everyone who asks receives; those who seek find; and to those who knock, the door will be opened.
“Which of you, if your son asks for bread, will give him a stone? Or if he asks for a fish, will give him a snake? If you, then, though you are evil, know how to give good gifts to your children, how much more will your Father in heaven give good gifts to those who ask him! So in everything, do to others what you would have them do to you, for this sums up the Law and the Prophets.
“Enter through the narrow gate. For wide is the gate and broad is the road that leads to destruction, and many enter through it. But small is the gate and narrow the road that leads to life, and only a few find it.
Not all whom we love should be received into friendship, for not all are suitable for it. Your friend is the companion of your soul, whose spirit is united and joined to yours, and, yes, you wish to be mingled such two are blended into one; you entrust to your friend as to another self, hiding nothing, and from whom you fear nothing.
Certainly, then, you should first choose someone whom you judge apt for this; then you test or try him or her to make sure, and finally you admit the person to friendship. For once friendship is commenced, it should be ever stable, in a sense mirroring eternity, always preserving your loving affection for each other.
We are not to be like children, changing our friendships upon every transient whim. For there is no one more detestable than the one who hurts a friend, and nothing is a greater spiritual torment than desertion from a friend, or an attack from a friend. So a friend must be chosen with all studiousness, and tested with the greatest caution.
But once admitted, however, your friend should be so tolerated, so borne with, so deferred to that, so long as they don’t retreat irrevocably from standard human norms, they are yours, and you are theirs, both in body and in spirit, such that there is no division in your spirits, affections, wills, or purposes. We distinguish, therefore, four rungs by which one ascends to the perfection of friendship: The first is choosing, the second testing, the third admission, and the fourth—in things both divine and human, with all charity and benevolence—completely harmonious unity.
—Aelred of Rievaulx (1110-1167) Spiritual Friendship 3.6-8