Praise be to Allaah.
This hadeeth was narrated by Ibn Maajah in his Sunan (4039).
Almost all the muhadditheen (hadeeth scholars) are agreed that this hadeeth is da’eef (weak)”
It was classed as da’eef by al-Bayhaqi, al-Haakim, Shaykh al-Islam Ibn Taymiyah in Manhaaj al-Sunnah (8/256), and Ibn al-Qayyim in al-Manaar al-Muneef (p. 148).
Al-Dhahabi said in Meezaan al-I’tidal (3/535): it is a munkar report.
Al-Qaari said in Mirqaat al-Mafaateeh (10/183): it is da’eef according to the consensus of the muhadditheen.
It was mentioned by al-Shawkaani in al-Fawaa’id al-Majmoo’ah, 127. He said: al-San’aani said: (it is) mawdoo’ (fabricated).
Al-Albaani said in Silsilat al-Ahaadeeth al-Da’eefah (77): It is munkar.
Even if this hadeeth were saheeh – but it is not saheeh – the meaning would be that there is no one who perfectly guided (mahdi) or protected from sin and error except ‘Eesa ibn Maryam. This was stated by al-Qurtubi, Ibn al-Qayyim and Ibn Katheer.
This does not contradict the fact that the Mahdi will emerge at the end of time and that he will join forces with ‘Eesa ibn Maryam (peace be upon him), and ‘Eesa will pray behind him in congregation.
We have already stated in the answer to question no. 1252 the evidence showing that the Mahdi will emerge at the end of time with the attributes that the Prophet (peace and blessings of Allaah be upon him) described. These saheeh ahaadeeth cannot be contradicted by a da’eef hadeeth like this one.
See al-Ahaadeeth al-Da’eefah, 1/89 by al-Albaani. Al-Mawsoo’ah fi Ahaadeeth al-Mahdi al-Da’eefah wa’l-Mawdoo’ah by al-Bastawi, p. 94-104.