C. F. Keil and Franz Delitzsch on Proverbs 1:18

Pro 1:18

The causal conj. כּי (for) in Pro 1:16 and Pro 1:17 are coordinated; and there now follows, introduced by the conj. ו (“and”), a third reason for the warning:

And they lie in wait for their own blood,

They lay snares for their own lives.

The warning of Pro 1:16 is founded on the immorality of the conduct of the enticer; that of Pro 1:17 on the audaciousness of the seduction as such, and now on the self-destruction which the robber and murderer bring upon themselves: they wish to murder others, but, as the result shows, they only murder themselves. The expression is shaped after Pro 1:11, as if it were: They lay snares, as they themselves say, for the blood of others; but it is in reality for their own blood: they certainly lie in wait, as they say; but not, as they add, for the innocent, but for their own lives (Fl.). Instead of לדמם, there might be used לדמיהם, after Mic 7:2; but לנפשׁם would signify ipsis (post-biblical, לעצמם), while לנפשׁתם leaves unobliterated the idea of the life: animis ipsorum; for if the O.T. language seeks to express ipse in any other way than by the personal pronoun spoken emphatically, this is done by the addition of נפשׁ (Isa 53:11). המו was on this account necessary, because Pro 1:17 has another subject (cf. Psa 63:10).