Or, He ascends the mountain to shew that the precepts of righteousness given by God through the Prophets to the Jews, who were yet under the bondage of fear, were the lesser commandments; but that by His own Son were given the greater commandments to a people which He had determined to deliver by love.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: de Serm. Dom. in Mont. i. 1