John Wesley on Proverbs 30:15

The horse - leach - An insatiable creature, sucking blood 'till it is ready to burst. Two daughters - The following things resemble the horse - leach in its insatiableness; nothing being more ordinary than to call those persons or things the sons or daughters of those whose examples they imitate. Three - Though he begins with two, yet he proceeds from thence to three, and four, all which are said to be the daughters of the horse - leach.