From The Gospel of Matthew by Curtis Mitch and Edward Sri, reflecting on Matthew 15:21-28:
Much can be learned by reflecting on the words and actions of the Canaanite woman. Among other things, she is a model for effective prayer. First, notice that she comes to the Savior with faith. She never questions whether Jesus is able to deliver her daughter from the demon. She simply trusts in the divine authority of Jesus, three times calling him “Lord.” Second, she shows perseverance in asking for Jesus’ help. Neither his initial silence nor his attempt to decline the request lessened her tenacity in pursuing his assistance. She persisted until she attained what she sought.