Charles Spurgeon Commentary Jeremiah 17:9

"The heart is deceitful above all things, and it is exceedingly corrupt: who can know it?" — Jeremiah 17:9 (ASV)

The heart-

That is the principal matter, it was the heart of the nation which had gone astray from God: "The heart"-

Is deceitful above all things, and desperately wicked: who can know it? I the Lord search the heart, I try the reins, even to give every man according to his ways, and according to the fruit of his doings. As the partridge sits on eggs, and hatches them not; so he that gets riches, and not be right, shall leave them in the midst of his days, and at his end shall be a fool.

The prophet likens the man who gets riches by falsehood and oppression to a bird which has many eggs, too many for her to cover; consequently, though she sits on them, there is such a heap of eggs that none of them are hatched; they come to nothing.

I think I know some men who are very like that partridge. It would be a great mercy for them if they had only half of the eggs that they have, for all they get is the care and trouble of covering them, but no living joy comes out of them; the eggs are addled.

He who has not the grace of God in his heart is just like a bird sitting upon addled eggs. Poor soul! At his end he shall be a fool. He must therefore be something of a fool now, for he who pursues an end which shall end in folly is a fool to have such an end before him.