Who was Ibn Sayyaad? Was he the false messiah (al-maseeh al-dajjaal)?
Question

                I have read in some ahaadeeth about a strange person who appeared at the time of the Prophet  (peace and blessings of Allaah be upon him). His name was Ibn Sayyaad or Ibn Saa’id. Who was this man and what was he?
Praise be to Allah.Ibn Sayyaad’s name was Saafi, or ‘Abd-Allaah, ibn (the son of) Sayyaad or Saa’id. 
 He was one of the Jews of Madeenah, and it was said that he was one of the Ansaar. He was a child at the time when the Prophet  (peace and blessings of Allaah be upon him) came to Madeenah. It was also said that he became Muslim.
 Ibn Sayyaad was a dajjaal (a liar), and he used to tell fortunes, sometimes what he said came true, and sometimes it did not. He became famous among the people, and it was rumoured that he was the Dajjaal. The Prophet  (peace and blessings of Allaah be upon him) wanted to find out about him, so he used to go to him secretly, without revealing his identity to him, hoping to hear something from him. He also asked him some questions directly, to find out what he really was. He outlived the Prophet  (peace and blessings of Allaah be upon him), then he was lost on the day of al-Harrah. [comment deleted] 
The story of the Prophet  (peace and blessings of Allaah be upon him) and Ibn Sayyaad 
 ‘Abdaan told us, ‘Abd-Allaah informed us, from Yoonus from al-Zuhri, who said, Saalim ibn ‘Abd-Allaah informed me that Ibn ‘Umar (may Allaah be pleased with him) informed him that ‘Umar set out with the Prophet  (peace and blessings of Allaah be upon him) to look for Ibn Sayyaad, and they found him playing with some boys near the battlement of Banu Maghaalah. At that time Ibn Sayyaad was on the threshhold of adolescence. He did not notice anything until the Messenger of Allaah  (peace and blessings of Allaah be upon him) struck him on the back with his hand. Then he said to Ibn Sayyaad, “Do you bear witness that I am the Messenger of Allaah?” Ibn Sayyaad looked at him and said, “I bear witness that you are the Messenger of the unlettered.” Ibn Sayyaad said to the Prophet  (peace and blessings of Allaah be upon him), “Do you bear witness that I am the messenger of Allaah?” He ignored that and said, “I believe in Allaah and His Messengers.” Then he asked him, “What do you see?” Ibn Sayyaad said, “(Sometimes) a truthful one comes to me and (sometimes) a liar comes.” The Prophet  (peace and blessings of Allaah be upon him) said, “You have been confounded.” Then the Prophet  (peace and blessings of Allaah be upon him) said to him, “I am concealing something from you.” Ibn Sayyaad said, “It is al-dukh.” [Referring to Soorat al-Dukhaan]. The Prophet  (peace and blessings of Allaah be upon him) said to him, “Be off with you! You will never go beyond your rank.” ‘Umar (may Allaah be pleased with him) said, “Permit me to strike his neck (kill him), O Messenger of Allaah.” The Prophet  (peace and blessings of Allaah be upon him) said, “If he is he (the Dajjaal), then you will not be able to overpower him, and if he is not (the Dajjaal), then your killing him will not do any good.”Saalim said, I heard Ibn ‘Umar (may Allaah be pleased with him) say: After that the Messenger of Allaah  (peace and blessings of Allaah be upon him) and Ubayy ibn Ka’b set off to go to some date-palm trees where Ibn Sayyaad was. The Prophet  (peace and blessings of Allaah be upon him) concealed himself in order to hear something from Ibn Sayyaad before Ibn Sayyaad saw him. The Prophet  (peace and blessings of Allaah be upon him) saw him lying on his bed with a blanket around him from which was coming a murmuring sound. The mother of Ibn Sayyaad saw the Messenger of Allaah  (peace and blessings of Allaah be upon him) hiding behind the trunk of the palm-tree and said, “O Saaf!” – which was his name – “Here is Muhammad  (peace and blessings of Allaah be upon him)!” Then Ibn Sayyaad jumped up and the Prophet  (peace and blessings of Allaah be upon him) said, “If she had left him alone, things would have been made clear.” (Narrated by al-Bukhaari, 1355). 
“Battlement” refers to a structure like a fortress. 
Maghaalah was a tribe of the Ansaar. 
The Prophet  (peace and blessings of Allaah be upon him) wanted to talk to Ibn Sayyaad without him realizing who he was. 
“from which was coming a murmuring sound” means, a low voice, or moving the lips as in speech, or speaking in an indistinct manner. 
See Fath al-Baari for the commentary on the above hadeeth in Kitaab al-Janaa’iz of Saheeh al-Bukhaari.
 ·Was Ibn Sayyaad the great Dajjaal? 
 The hadeeth quoted above – which describes some of the features of Ibn Saayaad and how the Prophet  (peace and blessings of Allaah be upon him) examined him – indicates that the Prophet  (peace and blessings of Allaah be upon him) did not pass judgement on the matter of Ibn Sayyaad, because it was not revealed to him (by Wahy) whether he was the Dajjaal or not. 
 Many of the Sahaabah thought that Ibn Sayyaad was the Dajjaal. ‘Umar ibn al-Khattaab (may Allaah be pleased with him) swore that he was the Dajjaal in the presence of the Prophet  (peace and blessings of Allaah be upon him) and the Sahaabah, and the Prophet  (peace and blessings of Allaah be upon him) did not disapprove of that. Muhammad ibn al-Munkadir said, “I saw Jaabir ibn ‘Abd-Allaah swear by Allaah that Ibn al-Saa’id was the Dajjaal. I said, ‘Do you swear by Allaah?’ He said, ‘I heard ‘Umar ibn al-Khattaab swear to that effect in the presence of the Prophet  (peace and blessings of Allaah be upon him), and the Prophet  (peace and blessings of Allaah be upon him) did not disapprove of that.’” (Narrated by al-Bukhaari, 6808). 
Ibn ‘Umar told a strange story about Ibn Sayyaad which was narrated in Saheeh Muslim from Naafi’, who said: Ibn ‘Umar met Ibn Sayyaad on one of the paths of Madeenah, and said to him something which made him so angry that he swelled up and filled the road. Ibn ‘Umar went to Hafsah and told her about this. She said, “May Allaah have mercy upon you! Why did you upset Ibn Sayyaad? Don’t you know that the Messenger of Allaah  (peace and blessings of Allaah be upon him) said that he (the Dajjaal) will emerge when something makes him very angry?” (Saheeh Muslim, 2932) 
In spite of that, when Ibn Sayyaad grew up, hetried to defend himself and said that he was not the Dajjaal; he was apparently upset by this accusation, and he quoted as evidence the fact that the attributes of the Dajjaal described by the Prophet  (peace and blessings of Allaah be upon him) did not apply to him.
 Abu Sa’eed al-Khudri said: “We went out for Hajj or ‘Umrah, and Ibn Saa’id was with us. We stopped at a place to camp, and the people separated and I was left with him (Ibn Saa’id). I felt very nervous and afraid of him, because of what had been said about him. He brought his luggage and put it with mine. I said, ‘It is very hot – why don’t you put your things under that tree?’ So he did that. Then some sheep appeared before us, and he went and brought a large vessel (of milk) and said, ‘Drink, O Abu Sa’eed.’ I said, ‘It is too hot, and the milk is hot.’ In fact (the only thing wrong was) that I did not want to drink from his hand, or take anything from his hand. He said, ‘Abu Sa’eed, I have been thinking that I should take a rope and suspend it from a tree, and hang myself, because of what people are saying about me. O Abu Sa’eed, does anyone know more about hadeeth than you Ansaar? Are you not one of the most knowledgeable of people about the hadeeth of the Messenger of Allaah  (peace and blessings of Allaah be upon him)? Didn’t the Messenger of Allaah  (peace and blessings of Allaah be upon him) say that the Dajjaal is a kaafir, and I am a Muslim? Didn’t the Messenger of Allaah  (peace and blessings of Allaah be upon him) say that he would be sterile, with no children, and I have left my child behind in Madeenah? Didn’t the Messenger of Allaah  (peace and blessings of Allaah be upon him) say that he will never enter Madeenah or Makkah, but I have left Madeenah and am headed for Makkah?’ … I was about to accept his excuses, then he said, ‘But, by Allaah, I know who the Dajjaal is, where he was born and where he is now.’ I said to him, ‘May you perish for the rest of the day!’” (Narrated by Muslim, no. 5211). 
 According to another report, Ibn Sayyaad said: “By Allaah, I know where he is now and I know his father and mother.” It was said to him, “Would you not be happy to be that man?” He said, “If it were offered to me, I would not refuse.” (Narrated by Muslim, 521) 
 The scholars were confused by the reports about Ibn Sayyaad. Some scholars said that he was the Dajjaal, and others said that he was not. Both groups had evidence (daleel) for what they said, and their views conflicted a great deal. Ibn Hajar tried to reconcile the two views by saying: the best way in which we may reconcile what is said in the hadeeth of Tameem al-Daari and the view that Ibn Sayyaad was the Dajjaal is to say that the Dajjaal is the exact same person whom Tameem al-Daari saw chained up, and that Ibn Sayyaad was a shaytaan (a devil) who appeared in the image of the Dajjaal at that time, until he went to Isfahaan, where he hid with his qareen, until the appointed time comes when Allaah will decree that he should emerge. Because the matter is so confusing, al-Bukhaari, instead of attempting a reconciliation, narrated the hadeeth of Jaabir from ‘Umar, believing it to be more saheeh, and did not narrate the hadeeth of Faatimah bint Qays about the story of Tameem. (Fath al-Baari, 13/328)
It was said that Ibn Sayyaad was one of the dajjaals or liars, but he was not the greater Dajjaal. And Allaah knows best.