Unto me, who am less than the least of all saints, is this grace given, that I should preach among the Gentiles the unsearchable riches of Christ… – Ephesians 3:8

It is a great grace to be permitted to preach the gospel. I have sometimes said to you that when the prodigal came back to his father, and was received into his father’s house, no earthly parent, though he had quite forgiven him all the wildness of his son’s adventure, could wholly forget the waywardness of his disposition. He might condone the past without confiding in him for the future. If it were needful to send one of the sons to market with a bag of money, the good old father would, in all probability, say to himself, “I will send the elder son with it: he is better to be trusted; I would hardly like to put such a responsibility upon the young lad who has so lately been reclaimed.” I can fancy, without uttering a word to his younger son he would, discreetly (as you would say), trust the other with any weighty concerns. But our heavenly Father—oh, how He forgives us! He leaves no back reckonings, for though we used to be such sinners, some of us, and so injurious, after He forgave us, He committed to our charge not merely silver and gold, the perishable resources of time, but the priceless treasure of the gospel of Jesus Christ: He allowed us to go and tell to others “the unsearchable riches of Christ.” See ye not the impure giving, lessons on chastity, the intemperate teaching chastity? and mark ye not how he who persecuted the disciples in times past, now preacheth the faith he once destroyed? Oh, what deep mercy there is in Jesus! What wonderful grace there is in giving His commissions, that those that cursed Him themselves should intercede with Him for others; that those that despised Him should be permitted to honor Him; that those who broke His Sabbaths should nevertheless be helpful to His people in hallowing the Lord’s-day; that those who despised His word, and put it behind their back, should be the men to open it, and display the sweetness of it to their fellow men! Is not this grace? Methinks every time Paul preached Jesus Christ, he would say to himself: “I used to call Him the Nazarene; I abhorred Him and used opprobrious language, but herein is great mercy, boundless mercy, that He should take me to be His servant, to permit me to labor for His people and suffer for His sake.” ~ C.H. Spurgeon

https://www.blueletterbible.org/comm/spurgeon_charles/sermons/0992.cfm