Psalm 23:2 — "He maketh me to lie down in green pastures: he leadeth me beside the still waters" — describes provision that comes from the shepherd's initiative, not the sheep's earning. The new mother who cannot make herself rest, who is running on empty and cannot find the still water, is in the hands of a shepherd who leads, who makes the lying down happen, who provides the stillness. The pastoral image is relevant precisely because the new mother is not in control of the exhaustion — she is being led.
Lamentations 3:22–23 was written from inside devastation, not comfort: "his compassions fail not. They are new every morning." For the new mother living in the rhythm of night feedings and postpartum fog, morning is not necessarily relief — sometimes it is more of the same. But the mercy that is new every morning is not conditional on the morning feeling different. It is a theological constant: God's compassion does not run out between the 2 AM feeding and the 5 AM one.
Commentary is from a charismatic Protestant perspective, drawing on KJV text and public-domain sources including Spurgeon, Andrew Murray, and Matthew Henry.