مَرَرْتُ بِزَيْدٍ
Translation: I passed by Zayd.
مَرَرْ: past-tense verb built on sukūn on account of the attached subject tāʾ.
تُ: attached pronoun, subject.
بِ: preposition.
زَيْدٍ: genitive noun governed by bi-, visibly marked with kasra and tanwīn.
The prepositional phrase «بِزَيْدٍ» is linked to the verb «مَرَرْتُ».