Albert Barnes Commentary Jeremiah 8:9

"The wise men are put to shame, they are dismayed and taken: lo, they have rejected the word of Jehovah; and what manner of wisdom is in them?" — Jeremiah 8:9 (ASV)

They have rejected the word of the Lord - It became in the hands of the Soferim or scribes a mere code of ceremonial observance. Compare (Mark 7:13).