Albert Barnes Commentary Jeremiah 34:5

"thou shalt die in peace; and with the burnings of thy fathers, the former kings that were before thee, so shall they make a burning for thee; and they shall lament thee, [saying], Ah Lord! for I have spoken the word, saith Jehovah." — Jeremiah 34:5 (ASV)

In peace - See Jeremiah 12:12 note.

Burn odors - "Make a burning." The burning was probably that of piles of wood, and spices were added only as a special honor. It was not a Jewish custom to burn the dead. As these burnings depended upon the estimation in which the dead king was held, the verse implies a prosperous reign, such as Zedekiah might have had as an obedient vassal to Babylon.

I have pronounced the word - I have spoken the word.