Charles Ellicott Commentary Jeremiah 26:8

"And it came to pass, when Jeremiah had made an end of speaking all that Jehovah had commanded him to speak unto all the people, that the priests and the prophets and all the people laid hold on him, saying, Thou shalt surely die." — Jeremiah 26:8 (ASV)

Thou shalt surely die. —Better, as expressing the Hebrew emphasis of reduplication, Thou shalt die the death. The phrase is the same as in Genesis 2:17. The threat of the men of Anathoth (Jeremiah 11:21) is repeated by the priests and prophets of Jerusalem. They look on Jeremiah as one who has incurred the condemnation of Deuteronomy 18:20.