Note the contradiction in the following verses.
• Verse Ex09-06 discussing the plague of pestilence which killed the Egyptian animals states And HaShem did that thing on the morrow, and all the cattle of Egypt died; but of the cattle of the children of Israel died not one. ;
• Verse Ex10-26 discussing what the Jews intended to take when they left Egypt states Our cattle also shall go with us; there shall not a hoof be left behind; for thereof must we take to serve HaShem our G-d; and we know not with what we must serve HaShem, until we come thither.'
• Verse Ex14-07 discussing the pursuit of the Jews, by the Egyptian army, after they left, states And he took six hundred chosen chariots, and all the chariots of Egypt, and captains over all of them.

We see the contradiction hinted at by the underlined words:
• The Egyptians pursued the Jews, presumably with animal driven chariots
• But the Egyptian animals were all killed in the plague of pestilence
• and the Jews took their own animals when they left Egypt
So if the Jews took their animals and the Egyptian animals were killed where did the animals to drive the Egyptian chariots come from?

Rashi resolves this using the two aspects method of resoulution. We read in the plague of hail that there were two types of Egyptians---
• The animals of those who did not believe in God died from the hail
• The animals of those who did believe in God were gathered into the house and consequently did not die from the hail
Indeed, verses Ex09-18:21 states Behold, tomorrow about this time I will cause it to rain a very grievous hail, such as hath not been in Egypt since the day it was founded even until now. Now therefore send, hasten in thy cattle and all that thou hast in the field; for every man and beast that shall be found in the field, and shall not be brought home, the hail shall come down upon them, and they shall die.' He that feared the word of HaShem among the servants of Pharaoh made his servants and his cattle flee into the houses; and he that regarded not the word of HaShem left his servants and his cattle in the field.

So the resolution is simple: Pharoh pursued the Jews with the animals of those Egyptians who believed in God and gathered their animals in the house to avoid them dying from the hail.

Sermonic points: The sermonic point inferred from this Rashi is obvious and Rashi himself says it You should not even trust the believers amongst the wicked. For indeed those who believed in God and saved their animals from death then double-crossed God by donating their animals to pursue the Jews.