جَاءَ الَّذِي أَبُوهُ قَائِمٌ.
Translation: The person whose father is standing came.
جَاءَ: past-tense verb.
الَّذِي: indeclinable relative noun in the nominative position as subject.
أَبُوهُ: «أَبُو» is a nominative mubtadaʾ marked by wāw (one of the six nouns), and muḍāf; «هُ» is its possessive pronoun and the ʿāʾid.
قَائِمٌ: nominative predicate.
The nominal sentence «أَبُوهُ قَائِمٌ» is the ṣilah, with no independent case position.