Increase in Yield of products in an exothermic reaction
Look, you say: "which was initially in equilibrium". Then the temperature are stable. In the reaction you have four mols in the reactants and 2 mols in the products. When you increase the temperature the system pressure increase too.

So to increase the stability the system "walk" for the reactants, because this decrease the pressure (2 mols in products and 4 mols in reactants).

If you remember the gas ideal law, the pressure is directly proportional to the mol numbers. So this is the reason because the temperature favor the products.