Matthew 23:24

24.Blind guides. This is s proverbial saying, by which he beautifully describes the affected scrupulousness of hypocrites about trifling matters; for they utterly shrink from very small faults, as if a single transgression appeared to them more revolting than a hundred deaths, and yet they freely permit themselves and others to commit the most heinous crimes. They act as absurdly as if a man were to strain out a small crumb of bread, and to swallow a whole loaf.

Straining out (101) a gnat, and swallowing a camel. We know that a gnat is a very small animal, and that a camel is a huge beast. Nothing therefore could be more ridiculous than to strain out the wine or the water, so as not to hurt the jaws by swallowing a gnat, and yet carelessly to gulp down a camel. (102) But it is evident that hypocrites amuse themselves with such distinctions; for while they pass by judgment, mercy, and faith, and even tear in pieces the whole Law, they are excessively rigid and severe in matters that are of no great importance; and while in this way they pretend to kiss the feet of God, they proudly spit in his face.