The backslider in heart shall be filled with his own ways: and a good man shall be satisfied from himself.
The backslider in heart (Psalms 44:18) shall be filled with his own ways - (note Proverbs 1:31.) Not one who turns aside from the right path of doctrine and practice through thoughtlessness, and, as it were, only with the feet, like one for the time intoxicated, but one who knowingly and willfully 'backslides in heart' - i:e., with the understanding and will-such a one shall get his fill of his own ways, until he shall nauseate and feel them his most terrible curse (cf. Numbers 11:19-20).
And a good man (shall be satisfied) from himself - `from that which is in himself.' His happiness is self-contained. Having God within, he is satisfied already, independently of other and external sources of happiness; and hereafter he shall be fully 'satisfied when he shall awake with his Lord's likeness' (Psalms 17:15), The ways of the godly man and his own regenerate heart shall become the source of his happiness, as the ways and the heart of the backslider shall be his misery.