Leviticus 11:43

43Ye shall not make yourselves abominable. He does not invite them to take care of their health, nor warn them of the danger of contracting’ diseases, but bids them beware of defiling themselves. And a clearer explanation is subjoined, “For I am the Lord your God: ye shall therefore sanctify yourselves; for I am holy.” Lest they should imagine that the main part of religion was contained in external ceremonies, they were to consider the nature of God; for, inasmuch as He is a Spirit, He would be worshipped only spiritually. Thus holiness is only connected instrumentally with the distinction of meats; since their abstinence had no other object than that they should consecrate themselves to God. Therefore the superstition of the Jews was inexcusable, when they satisfied themselves with trifling observances; (47) as if one should learn the letters of the alphabet without applying them to their use, and reading what is written. From their example we perceive how eagerly men lay hold of everything they can to sustain them in their hypocrisy, for they not only wrested to their earthly notions the things which were profitable in the pursuit of true integrity of heart; but, not content, with this, they heaped to themselves many supererogatory rites; (48) hence the water of expiation, or lustration always in use, even when they were unconscious of any pollution: hence their anxious labor in washing cups and platters, that it might readily appear how constantly the perversity of man abuses what God has appointed for the best of reasons.