your ear be open to God—and shut to sin.
1. We must watch our eye. "I made a covenant with my eyes." Job 31:1. Much sin comes in by the eye. When Eve saw that the tree was good for food, and pleasant to the eyes—then she took. Gen 3:6. First she looked—and then she lusted. The eye, by beholding an impure object, sets the heart on fire. The devil often creeps in at the window of the eye. Watch your eyes!
2. Watch your ear. Much poison is conveyed through the ear. Let your ear be open to God—and shut to sin.
3. Watch your hearts. We watch suspicious people. "The human heart is most deceitful and desperately wicked." Jer 17:9. Watch your heart:
[1] When you are about holy things, it will be slipping out to vanity. "When I am at prayer," says Jerome, "either I am walking through galleries or casting up accounts."
[2] Watch your hearts when you are in company. The basilisk poisons the herbs he breathes on. Just so, the breath of the wicked is infectious. Nay, watch your hearts when you are in good company. Such as have some good in them may be some grains too light, and have much levity of discourse; so that, if no scum boils up—yet there may be too much froth. The devil is subtle, and he can as well creep into the dove as he did once into the serpent. Satan tempted Christ by an apostle.
[3] Watch your hearts in prosperity. Now you are in danger of pride. The higher the water of the Themes rises, the higher the boat is lifted up. Just so, the higher men's estates rise, the higher their hearts are lifted up in pride. In prosperity, you are in danger not only to forget God—but to lift up the heel against him. "Jeshurun waxed fat, and kicked." Deut 32:15. It is hard to carry a full cup without spilling.