This hadeeth was not narrated via a saheeh isnaad from the Prophet (peace and blessings of Allaah be upon him). It has three isnaads from Anas, all of which are da’eef (weak).
It was narrated via Abu Ja’far al-Raazi from al-Rabee’ ibn Anas from Anas ibn Maalik (may Allaah be pleased with him). This version says that the Prophet (peace and blessings of Allaah be upon him) recited Qunoot for a month, praying against them, then he stopped, but in Fajr prayer he did not stop reciting Qunoot until he departed this world.
This was narrated by ‘Abd al-Razzaaq in al-Musannaf (3/110), and via him by al-Daaraqutni in al-Sunan (2/39). It was also narrated in brief by Ibn Abi Shaybah in al-Musannaf (2/312), al-Bazzaar (Kashf al-Astaar, 556), Ahmad in al-Musnad (3/162), al-Tahhaawi in Sharh Ma’aani al-Athaar (1/143), al-Haakim in al-Arba’een and from him by al-Bayhaqi in al-Sunan (2/201).
Abu Ja’far al-Raazi’s name was ‘Eesa ibn Maahaan al-Raazi. He was classed as da’eef (weak) by many scholars.
Ahmad ibn Hanbal said: He is not strong (qawiy) in hadeeth. Yahya ibn Ma’een said: He writes his hadeeth but he makes mistakes. ‘Amr ibn ‘Ali said: There is some weakness in him; he is sincere but he has a bad memory. Abu Zur’ah said: An old man who is often confused. Al-Nasaa’i said: He is not strong. Ibn Hibbaan said: He differed from the well known narrators of hadeeth by narrating munkar reports, and I would not like to quote his hadeeth as evidence except in cases where he narrated something that was also narrated by trustworthy narrators. Al-‘Ajli said: He is not strong. End quote from Tahdheeb al-Tahdheeb (12/57).
Via Ismaa’eel al-Makki and ‘Amr ibn ‘Ubayd from al-Hasan from Anas. This version says: The Messenger of Allaah (peace and blessings of Allaah be upon him), Abu Bakr, ‘Umar and ‘Uthmaan – and I think he said: a fourth – recited Qunoot until they left me.
This was narrated by al-Tahhaawi in Sharh Ma’aani al-Athaar (1/243), al-Daaraqutni in al-Sunan (2/40) and al-Bayhaqi in al-Sunan al-Kubra (2/202).
Ismaa’eel ibn Muslim al-Makki and ‘Amr ibn ‘Ubayd al-Mu’tazili: both of them are da’eef (weak) and their ahaadeeth are not to be used as evidence. There follow some comments of the scholars concerning them:
Ismaa’eel ibn Muslim al-Makki: concerning his biography it says in Tahdheeb al-Tahdheeb (1/332):
Ahmad ibn Hanbal said: his hadeeth is munkar. Ibn Ma’een said: He is nothing. ‘Ali ibn al-Madeeni said: His hadeeth is not to be written down. Abu Haatim said: He is da’eef and his hadeeth is confused. I said to him: Is he dearer to you or ‘Amr ibn ‘Ubayd? He said: Both of them are weak. Al-Nasaa’i said: His hadeeth is to be ignored. Ibn Hibbaan said: He is weak and narrated munkar ahaadeeth from well known narrators, and he mixes up the isnaads. End quote.
‘Amr ibn ‘Ubayd al-Mu’tazili is matrook al-hadeeth (i.e., his ahaadeeth are to be ignored). He told lies about al-Hasan. It says concerning his biography in Tahdheeb al-Tahdheeb (8/62):
Ibn Ma’een said: He is nothing. ‘Amr ibn ‘Ali said: His hadeeth is to be rejected and he is a follower of innovation (bid’ah). Abu Haatim said: his hadeeth is to be rejected. Al-Nasaa’i said: he is not trustworthy and his hadeeth is not to be written down. Abu Dawood al-Tayaalisi said, narrating from Shu’bah, from Yoonus ibn ‘Ubayd: ‘Amr ibn ‘Ubayd told lies in hadeeth. Humayd said: Do not take anything from him, because he told lies about al-Hasan. Ibn ‘Awn said: ‘Amr tells lies about al-Hasan. End quote.
Via Dinar ibn ‘Abd-Allaah, the servant of Anas ibn Maalik. This version says: The Messenger of Allaah (peace and blessings of Allaah be upon him) continued to recite Qunoot in Fajr prayer until he died.
Shaykh al-Albaani (may Allaah have mercy on him) said in al-Silsilah al-Da’eefah (3/386): This was narrated by al-Khateeb in Kitaab al-Qunoot, and Ibn al-Jawzi criticized him severely because of it, because Ibn Hibbaan said concerning this Dinar: he narrated fabricated reports from Anas which it is not permissible to quote in books except to demonstrate his weakness. End quote.
A number of scholars judged this hadeeth to be da’eef (weak) and invalid to be quoted as evidence, including Ibn al-Jawzi in al-‘Ilal al-Mutanaahiyah (1/444), Ibn al-Turkmaani in al-Ta’leeq ‘ala al-Bayhaqi, Ibn Taymiyah in Majmoo’ al-Fataawa (22/374), Ibn al-Qayyim in Zaad al-Ma’aad (1/99), al-Haafiz Ibn Hajar in al-Talkhees al-Habeer (1/245) and, among later scholars, al-Albaani in al-Silsilah al-Da’eefah (1/1238).
With regard to the ruling on Qunoot in Fajr prayer other than at times of calamity, this has been discussed in the answer to question no. 20031. The correct view is the view of Abu Haneefah and Ahmad, which is that it is not prescribed, because it is not proven via any saheeh isnaad that the Prophet (peace and blessings of Allaah be upon him) persisted in reciting Qunoot in Fajr prayer until he departed this world.
And Allaah knows best.