Aba Al-Fadl Al-Abbas (peace be upon him) emerged in the Islamic history as the greatest leader thanks to his heroism and all his other morals that are the finest in all earth languages.
On the day of At-Taf, Aba Al-Fadl (peace be upon him) has shown enormous resilience and indescribable solid will, and he was with his equanimity and strong resolve alone, a whole army that has frightened the army of Ibn Ziyad, and he has defeated them psychologically like he defeated them in the fields of war, as the heroism of Aba Al-Fadl was and still the example in the battlefields throughout the times.
By his supreme sacrifice, Abbas became a universal soul that transcends time and space. Imam As-Sadeq (peace be upon him) testified about the great morals of Aba Al-Fadl saying: "Our uncle Al-Abbas had a penetrating insight and a firm faith, he fought along with my father Aba Abdillah [Imam Al-Hussayn] (peace be upon him) and he has done well and died as a martyr."
The text of the Ziyarat we recite when we want to perform the Ziyarat rituals of Aba al-Fadl al-Abbas (peace be upon him), is indeed reported by Abi Hamza al-Thumali who stated that Imam Ja'far as-Sadeq (peace be upon him) said: "If you intend to visit the tomb of al-Abbas Ibn Ali (peace be upon both of them) that lies on the bank of the River Euphrates, you should stop at the gate of the shed and say these words:
Salam [peace] of Allah and Salam [peace] of His High-Ranked Angels, His prophets who were sent as Messengers, His Righteous Slaves, all of the Martyrs and the Truthful Ones, and all of the Purified and Blessed greetings be upon you at all times, O son of the Commander of the Believers. I testify that you submitted and that you devoted yourself and remained loyal to the Remainder of the Prophet who was sent as a Messenger (Imam Al-Hussayn "peace be upon him"), the Chosen Grandson, the Knowledgeable Guide, the Successor who announced (the message of Allah), and the one who was oppressed and wronged. May Allah reward you on behalf of his Messenger, the Commander of the Believers, Hassan and Hussein – may Allah's blessings be upon them – with the best of rewards, for you suffered (in this world) but remained patient expecting the reward from Allah. So how excellent is (your) final abode!! May Allah's curse be upon those who killed you. May Allah's curse be upon those who ignored your rights and breached your sanctity. May Allah's curse be upon those who stood between you and the water of the Euphrates (river). I testify that you were killed unjustly and verily Allah will fulfill that which He promised you. I have come to you, O son of the Commander of the Believers, as your guest while my heart has submitted to you. I follow you and my support is prepared for you until Allah judges and He is the Best of Judges. I am with you and only with you and not with your enemies. I believe in you and in your return and I disbelieve in those who opposed you and killed you. May Allah kill the nation who killed you with their hands and tongues. Salam [peace] to you, O (Allah's) Righteous Slave who was obedient to Allah, to His Messenger, to the Commander of the Believers, and to Al-Hassan And Al-Hussayn "peace be upon both of them". Salam [peace] to you and Allah's Mercy, Blessings, and Pleasure be upon you, your soul, and your body. I testify and take Allah as Witness that you died on the same path as the martyrs in the Battle of Badr who fought in the way of Allah, that you remained loyal to Him in fighting against His enemies, that you striver hard in supporting His Divine Authorities, and that you kept harm away from His Loved Ones. May Allah rewards you with the best of rewards, the greatest rewards, the most increasing rewards, and with rewards which are above any reward (which He has ever) granted to those who remained loyal to their allegiance, who answered his call, and who obeyed His Divine Authorities. I testify that you strived hard with loyalty and put forth all of your efforts (in the way of Allah). Therefore, Allah resurrected you among the Martyrs, joined your soul with the souls of the Ever-Blessed Ones, and gave you the most spacious place in His Heavens and the best of its Chambers (as your abode). And He elevated your remembrance in the highest of places and raised you with "the Prophet, the Truthful Ones, the Martyrs, and the Righteous Ones, and excellent are these companions" Holy Quran (4:96). I testify that you were not weakened and you did not lose heart (while facing the enemies). Verily you died with insight about your affairs while following the Righteous Ones and prophets. May Allah unite us with you, with His Messengers, and His Divine Authorities in the dwellings of the Humble Ones. Verily He is the Most Merciful of the merciful ones. Bidding Farewell I bid farewell to you, leave you in the care of Allah, and send my Salam [peace] to you. We believe in Allah, His Messenger, His Book, and in that which His Messenger brought forth from Allah. O Allah Register us among those who testify. O Allah Do not make this the last time I visit the son of your prophet's brother. Sustain me with his Ziyarah [visit] for as long as you keep me alive. Resurrect me with him and with his fathers in the Heavens. O Allah! Acquaint me with him, with your Messenger, and with your Divine Authorities. O Allah! Send Your Blessings on Muhammad and his holy, purified, infallible family, and make me die while believing in You, believing in Your Messenger, believing in the Wilayah of Ali Ibnu Abi Talib "peace be upon both of them" and the Imams from his sons, and while dissociating from their enemies. Verily I am pleased with this, O Lord. And prayers be upon Mohammad and his holy Household.
Then pray and recite du'a for you, your parents and the believers.