وَكَثِيرَةٍ غُرَبَاؤُهَا مَجْهُولَةٍ تَرْجَى نَوَافِلُهَا وَيُخْشَى ذَامُهَا
And how many a large gathering has strangers unknown to one another: its additional gifts are hoped for, and its censure is feared.
Kathīratin qualifies an understood noun such as gathering or assembly. Ghurabāʾuhā majhūlah emphasizes how many strangers have come together; the poet turns from his horse to his standing in a difficult social environment.
Nawāfiluhā denotes extra benefits or gifts and dhāmuhā blame. The paired expressions present a gathering whose favour is desirable and whose disapproval has consequences.