* "Your" has been part of English for centuries, evolving from Old English "eower".
* "Ears" is also an old word, coming from Old English "eare".
Therefore, "your ears" as a phrase would have emerged naturally as people started using the words "your" and "ears" together to refer to someone's ears.
There isn't a single, specific historical moment we can point to as the origin of the phrase. It simply evolved over time as English itself evolved.