Why don't you do business with acquaintances on credit?

My husband personally opened a health club, rented a small room in frontispiece and did a little business. Because of his cheerful personality, he also made many friends. Because of this, many patients began to pay credit, and they didn't give it for a long time. My husband doesn't want it. We had a fight about it, which really bothered us. Please pay attention. What should we do?