Naomi took the child - This might do for Naomi, but it was bad for the child. A child, unless remarkably healthy and robust, will suffer considerably by being nursed by an old woman, especially if the child sleep with her. The aged gain refreshment and energy by sleeping with the young; and from the same means the young derive premature decrepitude. The vigor which is absorbed by the former is lost by the latter. It is a foolish and destructive custom to permit young children, which is a common case, to sleep with aged aunts and old grandmothers. Bacon's grand secret of the cure of old age, couched in so many obscure and enigmatical terms, is simply this: Let young persons sleep constantly with those who are aged and infirm. And it was on this principle that the physicians of David recommended a young healthy girl to sleep with David in his old age. They well knew that the aged infirm body of the king would absorb a considerable portion of healthy energy from the young woman.

And Naomi took the child, and laid it in her bosom,.... As a token of her most tender love and affection for it; this it is probable she did quickly after the birth of it:
and became a nurse unto it; that is, after the mother had suckled and weaned it, then she took it from her, and brought it up.

Naomi therefore adopted this grandson as her own child; she took the boy into her bosom, and became his nurse.