Numbers 28

Therefore, we know that above all faith should commend us to God. When we have faith, let us strive for our works to be perfect. For this is a full and perfect sacrifice, as the Lord himself teaches us, saying: 'You shall offer to me your gifts and offerings on my feast days, without detracting or dividing them; but offering them in full, intact, and perfect.' Now, the feast day of the Lord is where the grace of perfected virtues resides. Those who are truly perfect are those whose mind, having conquered the allurements of worldly anxieties and bodily pleasures, is free from the world and dedicated to God, not diminishing anything from the straight path of their direct intention, nor dividing the times of their own affections now to luxury, now to labor. Therefore, only the wise celebrate this solemnity, no one else. For it is difficult to find a soul immune to such passions.

Because they could not have borne it if when giving the law for the sabbath God had said, "Do your good works on the sabbath, but do not the works that are evil," therefore he restrained them from all alike. "You must do nothing at all," he says, and even so they were not kept in line. But in the very act of giving the law of the sabbath he signified, though in shaded language, that he restricts them from evil works only, for he says, "You must do no work, except what shall be done for your life." And in the temple too all went on each sabbath with even more diligence and double toil. Thus even by shadows he was secretly opening them to the truth.