وَرَاوَدَتْهُ الَّتِي هُوَ فِي بَيْتِهَا عَنْ نَفْسِهِ
The woman in whose house he lived sought to entice him concerning himself.
Instead of naming the woman, the verse introduces her as the one in whose home Joseph lived. This highlights proximity, access, and the unequal circumstances in which she approached him. Against that background, the account of his chastity acquires additional force.
The relative clause does more than identify the woman; it contributes to establishing the intended portrayal of Joseph's integrity (عفة يوسف).