Farazdaq, in this poem, refers to the occasion when the Caliph Hisham b. Abd al Malik was overshadowed by the respect which people showed towards the great grandson of the Holy Prophet (pbuh&hf), at the time of Hajj when both of the individuals were trying to reach the crowds around the Kaab'ah to get to the black stone.
The people gave way to the Imam (as) while the Caliph struggled desperately. The Caliph, deeply offended, inquired in a sarcastic tone, who the person was who people had shown such preference. Farazdaq, who was also present at the moment composed an ode and recited it, addressing himself to Hisham.
Ref: al Sahifat as Sajidiyya
Contributed by Br. Ali Abbas, email@example.com