Like as a father pitieth his children - Hebrew, “Like the compassion of a father for his children.” See the notes at Matthew 7:7-11. God often compares himself with a father, and it is by carrying out our ideas of what enters into the parental character that we get our best conceptions of the character of God. See the notes at Matthew 6:9. That which is referred to here, is the natural affection of the parent for the child; the tender love which is borne by the parent for his offspring; the disposition to care for its needs; the readiness to forgive when an offence has been committed. Compare Luke 15:22-24. Such, in an infinitely higher degree, is the compassion - the kindness - which God has for those that love him.
So the Lord pitieth them that fear him - He has compassion on them. He exercises toward them the paternal feeling.