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.
It is someone whose footsteps are known by every place
And it is he who is known to the Bayt in Mecca
the most frequented sanctuary;
It is he who is the son of the best of all men of God
and it is he who is the most pious and devout,
the purest and most unstained
the chastest and most righteous
a symbol [for Islam]
This is Ali [b. al Husayn] whose parent is the Prophet
This is the son of Fatima, if you do not know who he is
Whosoever recognizes his God knows also
the primacy and superiority of this man
Because the religion has reached nations
through his House.