مَرَرْتُ بِأَحْمَدَ
Translation: I passed by Aḥmad.
مَرَرْ: past-tense verb built on sukūn with subject tāʾ.
تُ: attached subject pronoun.
بِ: preposition.
أَحْمَدَ: genitive noun governed by bi-, marked with visible fatḥa instead of kasra because it is a diptote.
“Genitive with fatḥa” names the syntactic case (genitive) and its unusual visible marker (fatḥa).