Then you will know that I am the LORD.
Mentioned a good sixty five or more times through Ezekiel, God makes it clear that He is the Sovereign LORD - the One who will judge, the One who will rescue, the One who is true to His promises.
In the days of oral tradition, repetition made it easier to remember what was being passed down from one hearer to the next by word of mouth. But I think there is more to the repetition than that. Having eyes open to these phrases deepens the reading and points to key themes.
Here are some others from the early books of the Old Testament that help make sense of these books.
Be holy because I am holy in Leviticus.
Remember me or Do not forget me (God, that is) in Deuteronomy.
Be courageous or Do not be afraid in Joshua.
In those days Israel had no king; everyone did as he saw fit in Judges.
Fear the LORD in Proverbs.
Look out for them as you read these books - and please let me know if you can think of any others.