John Wesley on Exodus 20:1

God spake all these words - The law of the ten commandments is a law of God's making; a law of his own speaking. God has many ways of speaking to the children of men by his spirit, conscience, providences; his voice in all which we ought carefully to attend to: but he never spake at any time upon any occasion so as he spake the ten commandments, which therefore we ought to hear with the more earnest heed. This law God had given to man before, it was written in his heart by nature; but sin had so defaced that writing, that it was necessary to revive the knowledge of it.