My soul is among lions - That is, among people who resemble lions; men, fierce, savage, ferocious.
And I lie even among them that are set on fire - We have a term of similar import in common use now, when we say that one is “inflamed” with passion, referring to one who is infuriated and enraged. So we speak of “burning” with rage or wrath - an expression derived, perhaps, from the inflamed “appearance” of a man in anger. The idea here is not that he “would” lie down calmly among those persons, as Prof. Alexander suggests, but that he actually “did” thus lie down. When he laid himself down at night, when he sought repose in sleep, he was surrounded by such persons, and seemed to be sleeping in the midst of them.
Even the sons of men - Yet they are not wild beasts, but “men” who seem to have the ferocious nature of wild beasts. The phrase, “sons of men,” is often used to denote men themselves.
Whose teeth are spears and arrows - Spears and arrows in their hands are what the teeth of wild beasts are.
And their tongue a sharp sword - The mention of the tongue here has reference, probably, to the abuse and slander to which he was exposed, and which was like a sharp sword that pierced even to the seat of life. See the notes at Psalms 55:21.