William Carey's "business" was to proclaim the Gospel!

William Carey, often called the "Founder of Modern Missions" was a minister, school-master, and a cobbler or shoe maker by trade before he left England to begin mission work in India. While still in England, he used to go about from village to village proclaiming the Gospel of Jesus Christ to the people.
One day a friend reportedly came to him and said,

"I want to speak to you very seriously."

"Well," said Carey, "What is it?"
His friend said, "By your going about talking to people as you do you're neglecting your business. If you only attended to making shoes more than you do, you would have a better business and could prosper far better than you are. But as it is you are simply neglecting your business."
To which Carey replied, "Neglecting my business? My business is to extend the Kingdom of God. I only cobble shoes to pay expenses!"
or as "Wholesome Words" website puts it, (click here)

"My real business is to preach the gospel and win lost souls. I cobble shoes to pay expenses."

Romans 10:13-15 (ESV)

13 For "everyone who calls on the name of the Lord will be saved."

14 How then will they call on Him in whom they have not believed? And how are they to believe in Him of whom they have never heard? And how are they to hear without someone preaching?
15 And how are they to preach unless they are sent? As it is written, "How beautiful are the feet of those who preach the Good News!"