Nor was Caesar without suspicions of him, and said once to his friends, "What do you think Cassius is aiming at? I don't like him, he looks so pale."
Plt Caesar Chapter 62: Caesar murdered; preliminaries

And when it was told him that Antony and Dolabella were in a plot against him, he said he did not fear such fat, luxurious men, but rather the pale, lean fellows, meaning Cassius and Brutus
Plt Caesar Chapter 62: Caesar murdered; preliminaries

It is not," said he, "these well fed, long-haired men that I fear, but the pale and the hungry looking;" meaning Brutus and Cassius.
Plt Antony Chapter 11: Caesar and Antony
By Julius Caesar