Jamieson, Fausset and Brown on Psalms 125:5

5. Those who turn aside (under temptation) permanently show that they are hypocrites, and their lot or portion shall be with the wicked (Psa 28:3).

crooked ways--(Compare De 9:16; Mal 2:8, 9).

their--is emphatic; the "crooked ways" proceed from their own hearts. The true Israel is here distinguished from the false. Scripture everywhere opposes the Jewish delusion that mere outward descent would save (Ro 2:28, 29; 9:6, 7; Ga 6:16). The byways of sin from the way of life.