Thomas Boston, Works, 3:209:
Search your own sins. Labour to prevent sins finding you out, by your finding out them. We should do in this case, as when one knows there is some hateful or venomous beast in their house; they search for it diligently till they find it out, lest it should come upon them unawares and do them harm. No serpent nor toad is such a dangerous guest as sin is. Search it out then, and search till you find it out.
Search your own sins. Labour to prevent sins finding you out, by your finding out them. We should do in this case, as when one knows there is some hateful or venomous beast in their house; they search for it diligently till they find it out, lest it should come upon them unawares and do them harm. No serpent nor toad is such a dangerous guest as sin is. Search it out then, and search till you find it out.