Therefore pray not you for this people, neither lift up a cry or prayer for them: for I will not hear them in the time that they cry unto me for their trouble.
Read Chapter 11
“Why do not Christians obtain all things in prayer?” Because they fail for many causes. They often ask things inexpedient. Why are you surprised, if this is the case with some, when even Paul heard: “My grace is sufficient for you, because my strength is perfected in weakness” … What if they pray against people who have hurt them, seeking for compensation and vengeance? This kind of thing is forbidden, for, “pray,” he said, “for your enemies.” … To Jeremiah he also said, “Do not pray for this people, for I will not hear you,” not wishing to stop Jeremiah from praying (for he earnestly longs for our salvation) but to terrify them. Thus the prophet, seeing this, did not cease praying. - "Homilies on the Gospel of Matthew 60.2"
They ask for a mercy it is impossible for them to receive since they have sins for which they have not repented. They cannot receive this mercy—not if they ask for it themselves, or even if the request is made by others who are stronger in their relationship with God. When Jeremiah was praying for the Jews, the Lord in fact said, “Do not pray for this people, because I will not hear you.” - "Homilies on the Gospel of Matthew 60.2"