The Haftarah for פרשת פרה is very beautiful and Messianic. It is from Yechezkel 36 and describes Mashiach.
It is well known from the Book of Isaiah, that the Mashiach can come in one of two ways. Either it will come בעיתה, in its designated time, or אחישנה, Hashem will hurry its coming. The Talmud clarifies this by saying the following:
זכו-אחישנה, לא זכו-בעיתה
If we deserve it, Hashem will hurry the coming of Mashiach. That is, if we collectively do Teshuva. If we do not deserve it, Mashiach will still come in the time Hashem decides is the correct time.
Most opinions are that we are living in the period of בעיתה. Our Haftarah clearly says that Hashem will rebuild the House of Israel, not because we deserve it, but for the sake of His holy Name.
He will pour waters of purification on us, similar to the פרה אדומה in order to purify us. This is the reason this Haftarah was chosen for פרשת פרה.