Why are you cast down, O my soul, and why are you in turmoil within me? Hope in God; for I shall again praise him, my salvation (Psalm 42:5). Notice that this call to worship comes from David, to David. It is David confronting his own doubting, discouraged heart with the truth of who God is.
And going into the house, they saw the child with Mary his mother, and they fell down and worshiped him. Then, opening their treasures, they offered him gifts, gold and frankincense and myrrh (Matthew 2:11) There is a library full of lessons in this single verse of Scripture.