Baalis - named from the idol Baal, as was often the case in heathen names.
Ammonites - So it was to them that Ishmael went after murdering Gedaliah (Jer 41:10).
slay - literally, “strike thee in the soul,” that is, a deadly stroke.
Ishmael - Being of the royal seed of David (Jer 41:1), he envied Gedaliah the presidency to which he thought himself entitled; therefore he leagued himself with the ancient heathen enemy of Judah.
believed ... not - generous, but unwise unsuspiciousness (Ecc 9:16).