…but smote upon his breast… – Luke 18:13

Note what the  publican did: he smote upon his breast… What did he smite his breast for? Because he knew where the mischief lay- in his breast…He smote upon his breast as if he were angry with himself. He seemed to say, “Oh! that I could smite thee, my ungrateful heart, the harder, that thou hast loved sin rather than God.” He did not do penance, and yet it was a kind of penance upon himself when he smote his breast again and again, and cried “Alas! alas! woe is me that I should ever have sinned against my God. God be merciful to me a sinner.” Now, can you come to God like this, my dear friend? Oh, let us all draw near to God in this fashion. Thou hast enough, my brother, to make thee stand alone for there have been sins in which thou and I have stood each of us in solitary guilt… Come, let each man now look to his own case, and not to the case of another, let each cry, “Lord, have mercy upon me, as here I stand alone, a sinner.” And hast thou not good reason to cast down thine eyes? Does it not seem sometimes too much for us ever to look to heaven again. We have blasphemed God, some of us, and even imprecated curses on our own limbs and eyes; and when those things come back to our memory we may well be ashamed to look up. Or if we have been preserved from the crime of open blasphemy, how often have you and I forgotten God! how often have we neglected prayer! how have we broken His Sabbaths and left His Bible unread! Surely these things as they flash across our memory, might constrain us to feel that we cannot lift up so much as our eyes towards heaven. And as for smiting on our breast, what man is there among us that need not do it? Let us be angry with ourselves, because we have provoked God to be angry with us. Let us be in wrath with the sins that have brought ruin upon our souls, let us drag the traitors out, and put them at once to a summary death; they deserve it well; they have been our ruin; let us be their destruction. ~ C.H. Spurgeon

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