Proverbs 30:15,16

The horseleach hath two daughters, crying, Give, give. There are three things that are never satisfied, yea, four things say not, It is enough:

Four insatiable things follow the four detestable offences.

The horse-leach hath two daughters, (crying), Give, give. The horse-leach is covetousness. The two words are, as it were, her two daughters, which come forth out of her. The greediness of the covetous is described in Proverbs 30:14. Not content with having once "devoured the needy," they again, a second time, return to drain out all their substance, like the horse-leach.

There are three (things) ... yea, four (things) - (cf. Amos 1:3, on the Hebrew idiom, "three yea, four.")

Verse 16. The grave ( shª'owl (H7585); cf. Proverbs 27:20); the world of departed spirits, ever craving for fresh comers from this world),

... the barren womb (cf. Rachel, Genesis 30:1);

The earth (that) is not filled with water (that is always ready to drink more rain);

And the fire (that) saith not (it is) enough - that is ready to consume any amount of fuel that you pile on it.