For the LORD shall be thy confidence, and shall keep thy foot from being taken. -Proverbs 3:26

“My bad works,” said Erskine, “Always drove me to the Saviour for mercy; my good works often kept me from Him, and I began to trust in myself.” Is it not so with us? We often get a pleasing opinion of ourselves: we are preaching so many times a week, we attend so many prayer meetings; we are doing good in the Sabbath-school; we are valuable deacons; important members of the church; we are giving away so much in charity; and we say, “Surely I am a child of God-I must be. I am an heir of heaven. Look at me! See what robes I wear. Have I not indeed a righteousness about me that proves me to be a child of God?” Then we begin to trust in ourselves, and say, “Surely I cannot be moved, my mountain standeth firm and fast.” …Many a Christian owes his falls to a presumptuous confidence in his graces. I conceive that outward sin is not more abhorbed by God than this most wicked sin of reliance on ourselves. May none of you ever learn your own weakness by reading a black book of your own backslidings. More to be desired is the other method of God when He sends the light of the Spirit into the heart, and developes our corruption; Satan comes roaring there, conscience begins calling out, “Man you are not perfect.” All the corruptions burst up like a volcano that had slept for a little moment. We are taken into the dark chambers of imagery; we look at ourselves, and say, “Where are my battlements gone?” We go to the hill-top again, and see the battlements are all gone. We go by the side of the city-they are all departed. Then we go again to Christ, and say,

“I, the chief of sinners am,
Jesus died for me.”
“Nothing in my hands I bring;
Simply to Thy cross I cling.”

Heaven smiles again, for now the heart is right, and the soul is in the most fitting position. Take care of your graces, Christians! ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/0038.cfm