L-B-B…Form I verb, He was Possessed of Understanding, Intellect, Intelligence…LaBB, noun, A Camel Driver Who Keeps Constantly to the Work of Driving the Camels…LaBBaika, At Your Service!, said by a Pilgrim approaching Mecca, meaning, Lord, Here I Am!
-Lane’s Lexicon
None of the drovers had performed the Hajj, so none ever had the occasion to say, Labbaika!, but they all were to some degree possessed of intelligence about camels, and so they kept constantly driving the Dabouka, approaching Masr.