Shemos 19:5 - the verse reads ועתה אם שמוע תשמעו בקלי ושמרתם את בריתי והייתם לי סגלה מכל העמים כי לי כל הארץ.
Targum translates Segula as beloved - חביבין
Rashi translates Segula as a beloved treasure - אוצר חביב
Currently the word Segula is mostly used as a remedy, protection, something that protects a person from harm or a benevolent charm.
What is the earliest known use of the word Segula, not as the original meaning of beloved?