My flesh and my heart faileth,.... Either through vehement desires of communion with God deferred, see Psalms 84:2 or through afflictive dispensations of Providence, being smitten and chastened continually, Psalms 73:14, or through inward trials and exercises, by reason of indwelling sin, temptations, and desertions: or rather the words are expressive of the body being emaciated by sickness and diseases; and the heart fainting through fear of death, or rather failing at it, being at the point of death; the heart being, as philosophers say, the first that lives, and the last that dies:
but God is the strength of my heart, or "the rock of my heart" h; when overwhelmed with distress through outward trouble, or in the lowest condition with respect to spiritual things; when grace is weak, corruptions strong, temptations prevail, and afflictions are many; then does the Lord support and sustain his people, and strengthens them with strength in their souls; and in the moment of death, by showing them that its sting is taken away, and its curse removed; that their souls are going to their Lord, and about to enter into his joy; and that their bodies will rise again glorious and incorruptible:
and my portion for ever; both in life and at death, and to all eternity; this is a very large portion indeed; such who have it inherit all things; yea, it is immense and inconceivable; it is a soul satisfying one, and is safe and secure; it can never be taken away, nor can it be spent; it will last always; see Psalms 142:5.
h וור לבבי "rupes cordis mei", Montanus, Musculus, Piscator, Cocceius, "petra cordis mei", Tigurine version, Gejerus, Michaelis; so Ainsworth.