19. living . . . living--emphatic repetition, as in Isa 38:11, 17; his heart is so full of the main object of his prayer that, for want of adequate words, he repeats the same word.
      father to the children--one generation of the living to another. He probably, also, hints at his own desire to live until he should have a child, the successor to his throne, to whom he might make known and so perpetuate the memory of God's truth.
      truth--faithfulness to His promises; especially in Hezekiah's case, His promise of hearing prayer.

JFB.