John Gill Commentary Jeremiah 41:15

"But Ishmael the son of Nethaniah escaped from Johanan with eight men, and went to the children of Ammon." — Jeremiah 41:15 (ASV)

But Ishmael the son of Nethaniah escaped from Johanan with
eight men
Of the ten he brought with him (Jeremiah 41:1); two of them being slain in this skirmish, or taken by Johanan, or they fled another way: and went to the Ammonites ;
who had put him upon, or however encouraged and assisted him in, his wicked attempts; though he returned to them not according to their wishes, nor with that honour and glory he thought to have done.