وَبِالْمُضَافِ إِلَى يَاءِ الْمُتَكَلِّمِ غَيْرِ جَمْعِ الْمُذَكَّرِ السَّالِمِ، كَـ«غُلَامِي».
Translation: This also applies to a noun annexed to the first-person singular yāʾ, excluding the sound masculine plural; for example, غُلَامِي (“my servant”).
The kasra before the possessive yāʾ fits that pronoun; it does not necessarily mean the noun is genitive.