وَ إِنَّمَا سُمِّيَ الْحَجُّ الْأَكْبَرَ لِأَنَّهَا كَانَتْ سَنَةً حَجَّ فِيهَا الْمُسْلِمُونَ
English translationBab Ul Qaim Publications
Hadith.2132 - The Hajj was called 'Al-Hajj Al-Akbar' (the Greater Pilgrimage) because it was the year in which both Muslims and polytheists performed the pilgrimage, and the polytheists did not perform Hajj after that year.
Translation: Bab Ul Qaim Publications·Thaqalayn link·The Arabic above is the original.