The great apostle Paul, like most Jewish men of his time, learned a trade, and even after his life’s work became spreading the gospel, he continued this trade, tentmaking.
His close friends Priscilla and Aquila, a married couple, engaged in the same trade (Acts 18:3).
Today people use “tentmaker ministry” to refer to pastors or missionaries who earn their income in a regular job while also working (sometimes for free, or for little pay) in their ministry.