Jeremiah
Jeremiah 41:11ESV·traditional attribution

But when Johanan the son of Kareah and all the leaders of the forces with him heard of all the evil that Ishmael the son of Nethaniah had done,

Matthew Henry Presbyterian @wholebiblehenry

It would have been well if Johanan, when he gave information to Gedaliah of Ishmael's treasonable design, though he could not obtain leave to kill Ishmael and to prevent it that way, yet had staid with Gedaliah; for he, and his captains, and their forces, might have been a life-guard to Gedaliah and a terror to Ishmael, and so have prevented the mischief without the...

Commenting on Jeremiah 41:11-18

John Gill Reformed Baptist @doctorgill

But when Johanan the son of Kareah,.... The same that is mentioned Jer 40:8; and who had informed Gedaliah of Ishmael's designs against him, but he would not believe him: and all the captains of the forces that were with him; his brother Jonathan, Seraiah, the sons of Ephai, and Jezaniah, Jer 40:8; heard of all the evil that Ishmael the son of Nethaniah had...

Jamieson-Fausset-Brown Reformed @jfbcommentary

Johanan--the friend of Gedaliah who had warned him of Ishmael's treachery, but in vain (Jer 40:8, Jer 40:13).