What Sham'oon, the successor of Isa said to ‘Ali (as)

Qais, the servant of ‘Ali ibn Abi Talib, peace be upon him, who said:
Once when ‘Ali, Amirul Mu’mineen was near the mountain at Siffin, the time for maghrib prayers set in. So he went farther away and called for the prayers. When he finished the Adhan, a man appeared from near the mountain, having grey hair and beard, with a bright, white face. He said: "Peace be upon you, O Amirul Mu’mineen and mercy and blessings from Allah! Welcome to the successor of the last of the Prophets, leader of the ones with bright, brilliant faces, (on the Day of Judgement) magnanimous and protected, excellent one and one who has the reward of the Truthfuls, master of all the successors!"
So, Amirul Mu’mineen, peace be upon him, said: "And peace be upon you, how are you?" He replied: "I am well, waiting for the holy spirit. I do not know of any name, which is greater in the estimation of Allah, at the time of ordeal, than yours, nor of any who has earned more rewards than you, nor of anyone who has an elevated place higher than yours. Put up with all that you are in, O my brother, till you meet the al-Habib (the beloved Prophet, peace be upon him and his progeny). Verily, I have witnessed whatever befall our colleagues in the past at the hands of the children of Israel. They cut them apart with the saw and carried them over the bier."
And then pointing towards the people of Syria, he said: "And if these poor, ugly faces know what chastisement and exemplary punishment awaits them for fighting against you, they would withdraw." And then pointing to the people of Iraq, he said: "And if these bright faces knew what award awaits them for having obeyed you, they would love to be cut by the scissors. And peace and His mercy and blessings be upon you." Then he disappeared.
At that time, Ammar ibn Yasir, Abdul Haytham ibn al-Teehan, Abu Ayyub al-Ansari, Ubadah ibn al-Samit, Khuzaima ibn Thabit and Hashim al-Marqal, a group from his followers stood up and said: "O, Amirul Mu’mineen, (for they heard what the man had said) who is this man?" Amirul Mu’mineen said: "He is Sham'oon, the successor of Isa, peace be upon him. Allah sent him to me to give me solace for this confrontation with His enemies!" They said: "May our parents be your ransom, By Allah, we will help you the way we helped the messenger of Allah, peace be upon him and his progeny, and none from the al-Muhajir nor al-Ansar shall desert you, except the unfortunate one." (Upon hearing this), Amirul Mu’mineen spoke to them kind words."