Charles H. Spurgeon on Psalms 81:4

For this was a statute for Israel, and a law of the God of Jacob. It was a precept binding upon all the tribes that a sacred season should be set apart to commemorate the Lord's mercy; and truly it was but the Lord's due, he had a right and a claim to such special homage. When it can be proved that the observance of Christmas, Whitsuntide, and other Popish festivals was ever instituted by a divine statute, we also will attend to them, but not till then. It is as much our duty to reject the traditions of men, as to observe the ordinances of the Lord. We ask concerning every rite and rubric, "Is this a law of the God of Jacob?" and if it be not clearly so, it is of no authority with us, who walk in Christian liberty.