وَصَلَ الرَّسُولُ ـ وَقَدْ طَالَ انْتِظَارُنَا ـ قُبَيْلَ الْفَجْرِ.
The messenger arrived—after we had waited a long time—just before dawn.
The main predication is waṣala al-rasūlu qubayla al-fajr. The intervening clause contributes the affective significance of prolonged anticipation without being needed to complete the main syntax. In a fitting context this can be read as iʿtirāḍ.
Because wa-qad ṭāla also bears a circumstantial flavor, formal grammar and rhetorical classification should not be collapsed. Context supplies the grounds for preferring one functional description.