It is said by God. the context is that a man is complaining about the misery of life and kind of scolding God for not making the world perfect. Then God asked him to see the other living things that He created, the lion with a strong body, the bird with wings which enable it to fly, etc. God said if He had given these living things so much, then how would He treat human beings any less better. So he called the man something like "you faithless creature".
In the New Testament, (Matthew) it speaks about how God takes care of the birds and the flowers, so it stands to reason that he would take care of humans even better. We should not worry about how we look or what we wear, the things in nature don't worry about those things.