Caesar must be undoubted Caesar.
2 seconds sound clip from the The Fall of the Roman Empire (1964) movie soundboard.
You can hear this line at 01:13:00.498 in the Blu-ray version of the movie.
Quote context
[...]
- You are looking for a document, Timonides? A document in which my father named me his heir.
- I will bare witness that it was Caesar's wish, that you'd be his heir.
- If it was only your word, Lucilla, there would be doubt.
- Caesar must be undoubted Caesar.
- Is it not possible, Lucilla, that there are other ways of becoming the real heir of Marcus Aurelius?
- Hail, undoubted Caesar! Hail Commodus! Hail Caesar! Hail Commodus!
- Hail Caesar! Hail Commodus! Hail Caesar! Hail Commodus!
- I will never forget what you have done today.
[...]