جَاءَ عُمَرُ
Translation: ʿUmar came.
جَاءَ: past-tense verb, built on fatḥ.
عُمَرُ: nominative subject marked by visible ḍamma.
The absence of tanwīn results from the noun's diptote status. Its function as subject determines nominative case; ʿadl + proper-name status explain its declension class.