Why was the issue of slavery so important to the delegates of the constitutional convention

The Constitutional Convention left the slave trade untaxed and untouched. Delegates from the southern States were naturally wary about the prospect of Congress being able to regulate America's interstate and foreign trade. They were afraid that the North would use its influence in Congress to levy taxes on the slave trade and the cotton trade. The delegates from the South pushed for, and won, a compromise on the matter: the Commerce and Slave Trade Compromise. This agreement made it so Congress could regulate interstate and foreign trade, but could not tax exports. This meant that cotton exports from the South would not be affected. In addition, Congress was forbidden from regulating the slave trade for 20 years. Hope this helps!