First of all, what is a business?
Business is the act of producing or buying and selling of goods to earn a profit. The profits made are mostly in monetary terms. If there is no motive of gaining a benefit in dealing, then that particular dealing will not be counted for business. Likewise, works done for social welfare will also not be counted for business. Also, transactions done once or casually will not be constituted as the business. In other words, the activity should be recurrent, i.e., it should be repetitive. The main aim of the company is to earn money.
Now coming on the point of the topic as to what is the first law of business;
The main aim of business is to earn money. And money can be received by selling the products. And product can be sold when the customer purchases it. And the customer will buy when he is satisfied with the product. So, the first law of business is to keep and create a customer. A customer is considered as the king of the market. A business can survive and grow in the long run only if the consumer is satisfied with the products and services of the business. It can retain the customers by following ways:
Providing the right products that the consumers require.
The business should not compromise on the quality of the product just for earning more profit
The industry should aim to provide the best aftersales services, etc.