“The publican stood afar off.”- Luke 18:13

We have often made general confessions in the temple, but there never was a confession accepted, except it was particular, personal, and heartfelt. There were the people gathered together for the accustomed service of worship; they join in a psalm of praise, but the poor publican stood far away from them. Anon, they unite in the order of prayer, still he could not go near them. No, he was come there for himself, and he must stand by himself. Like the wounded hart that seeks the deepest glades of the forest where it may bleed and die alone in profound solitude, so did this poor publican seem to feel he must be alone. You notice he does not say anything about other people in his prayer. “God be merciful to me,” he says. He does not say “one of a company of sinners,” but “a sinner,” as if there were not another sinner in all the world. Mark this, my hearer, that thou must feel thyself solitary and alone, before thou canst ever pray this prayer acceptably. Has the Lord ever picked thee out in a congregation? Has it seemed to you as if there were a great black wall round about you, and you were closed in with the preacher and with your God, and as if every shaft from the preacher’s bow was leveled at you, and every threatening meant for you, and every solemn upbraiding was an upbraiding for you? If thou hast felt this, I will congratulate thee. No man ever prayed this prayer aright unless he prayed alone, unless he said “God be merciful to me,” as a solitary, lonely sinner. “The publican stood afar off.” ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/0216.cfm