Jiʾtu is a first-person perfect, “I came.” The following wa-qad naḍḍat combines a circumstantial wāw with qad and a perfect to indicate that the action had already been completed at the time of arrival.
Naḍḍat means that she had taken off or laid aside clothes; its implicit subject is the woman, and thiyābahā is the object. Li-nawmin expresses purpose: for sleep.
The temporal sequence matters. Jiʾtu marks the arrival, whereas qad naḍḍat describes a prior state. The two verbs should not be flattened into an unordered list of simultaneous actions.