When Jesus said that He calls us His friends, He meant something more than we do most of the time. Too often, "friend" just means someone we recognise to wave at across the street, without muttering cuss words under the breath.
True friendship is so much beyond that, as we are taught in today's Office of Readings with the scriptural passage about the faithfulness of Jonathan, son and heir of King Saul, to David, the anointed of God.
St. Aelred commented on this in his treatise on Spiritual Friendship:
That outstanding youth, Jonathan, son of King Saul, made an alliance with David, but it was not in the hope of obtaining the royal crown or winning the kingdom. For the sake of their friendship, he set David above himself as if he had been his master and not his own father’s servant, expelled, hiding in the desert, sentenced to death, destined for execution --- he abased himself and raised David up: You will be king, he said, and I will be next below you in rank.
What an excellent example of true friendship! What a wonder! The king was raging against his servant and stirring up the whole country as if against a pretender to the throne. He accuses priests of treachery and has them killed on the mere suspicion --- he has the forests and the valleys searched --- he posts armed guards on cliffs and mountains. Everyone swears to punish the object of the king’s anger; but Jonathan, who alone has the right to envy the designated successor to the throne --- Jonathan chose to resist his father, keep his friend supplied with news, give him counsel in his adversity. Thinking it better to be a friend than a king: You will be king, he said, and I will be next below you in rank.
See how the father tried to make the young man envy his friend, how he goaded him with insults, threatened him with dispossession, and warned him of the honours he would lose. But even when Saul had condemned David to death, Jonathan did not fail his friend. “Why should David die? What has he done wrong? What has he done? It was he who took his life in his hands and struck down the Philistine --- you rejoiced, then. So why should he die?”
At these words the king was beside himself with rage and tried to pin Jonathan to the wall with his spear, pouring out new insults and threats. “Son of a wanton and lascivious woman! I know that you love him, to your own shame and the shame of your shameless mother!” Then he poured out on the young man all the venom he had in him. He tried to stir up ambition and envy, bitterness and jealousy in Jonathan’s breast: As long as the son of Jesse lives, your kingdom cannot be established.
Who would not have been moved to jealousy by these words? Whose love would not have been corrupted, grace diminished, friendship wiped out? But this most loving youth held fast to the oaths of friendship he had sworn, stood up to the threats, endured the insults, and disdained the kingdom for the sake of friendship, careless of the glory he would miss but mindful of the integrity he would keep. You will be king, he said, and I will be next below you in rank.
Here is a true and perfect friendship, solid and eternal: a friendship that envy does not corrupt, suspicion does not diminish or ambition wipe out. It does not cease even under such a trial; even under such a battering it does not collapse. Assailed with abuse, it stands firm; beaten with insults, it does not bend. Go thou, and do likewise.