وَحُكْمُهُ: أَنْ يَدْخُلَهُ الْحَرَكَاتُ الثَّلَاثُ مَعَ التَّنْوِينِ، تَقُولُ: «جَاءَنِي زَيْدٌ، وَرَأَيْتُ زَيْدًا، وَمَرَرْتُ بِزَيْدٍ».
Translation: Its rule is that it takes the three case vowels together with tanwīn: Zayd came to me; I saw Zayd; I passed by Zayd.
ZAYD takes a ḍamma plus tanwīn in the nominative, a fatḥa plus tanwīn in the accusative, and a kasra plus tanwīn in the genitive.