Jeremiah 9: boast in understanding the Lord

 In Jeremiah 9 we read:

5 Everyone deceives his neighbor
And does not speak the truth.
They have taught their tongue to speak lies;
They weary themselves committing wrongdoing.

The Lord will destroy Judah. One reason is that they have taught their tongue to speak lies. Some people say that it is sign of intelligence to lie; the Bible says it needs some learning to lie; however, the one who lies is in constant motion not to be caught, he can't rest.

9 Shall I not punish them for these things?” declares the Lord.
“Shall I not avenge Myself
On a nation such as this?
...
11 I will make Jerusalem a heap of ruins,
A haunt of jackals;
And I will make the cities of Judah a desolation without inhabitant.”
...
16 I will also scatter them among the nations, whom neither they nor their fathers have known; and I will send the sword after them until I have put an end to them.”
...

23 This is what the Lord says: “Let no wise man boast of his wisdom, nor let the mighty man boast of his might, nor a rich man boast of his riches; 24 but let the one who boasts boast of this, that he understands and knows Me, that I am the Lord who exercises [f]mercy, justice, and righteousness on the earth; for I delight in these things,” declares the Lord.

Everyone boasts on his own strength because it gives some advantage over others; however the great advantage is to know the Lord that is merciful, just and righteous and He wants his people to be so.

25 “Behold, the days are coming,” declares the Lord, “that I will punish all who are circumcised and yet uncircumcised— 26 Egypt, Judah, Edom, the sons of Ammon, Moab, and all those inhabiting the desert who trim the hair on their temples; for all the nations are uncircumcised, and all the house of Israel are uncircumcised of heart.”

Interestingly the Lord is not delighted to see the sign of the covenant (circumcision) without a heart circumcised.