How sound is the hadeeth, “Whoever sends blessings upon me eighty times on Friday, his sins will be forgiven for eighty years”?
Question

                I have a question about a hadeeth, according to which Abu Hurayrah (may Allah be pleased with him) said: “The one who recites eighty times after ‘Asr prayer on Friday, before he gets up from his place, Allah will forgive his sins for eighty years, and will record for him the reward of worshipping for eighty years,” and that is to say this dhikr eighty times: “O Allah, send blessings and peace upon Muhammad the unlettered Prophet.”

Is this hadeeth saheeh? Can I follow it? Because I see many people doing these things.
Praise be to Allah.
    This 
    hadeeth was narrated by Ibn Shaheen in at-Targheeb fi Fadaa’il al-A‘maal 
    (p. 14) via ‘Awn ibn ‘Umaarah, from Sakan al-Burjumi, from Hajjaaj ibn 
    Sinaan, from ‘Ali ibn Zayd, from Sa‘eed ibn al-Musayyib, from Abu Hurayrah, 
    who said: The Messenger of Allah (blessings and peace of Allah be upon him) 
    said: “Sending blessings upon me will be light on the siraat. Whoever sends 
    blessings upon me eighty times on Friday, his sins will be forgiven for 
    eighty years.” 

    Some of 
    the later scholars were lenient and classed this hadeeth as hasan; however 
    the correct view is that the hadeeth is da‘eef (weak), and in fact it is 
    da‘eef jiddan (very weak), because its isnaad includes three da‘eef 
    narrators, namely: 

    1.
    
    ‘Ali ibn 
    Zayd ibn Jad‘aan al-Basri 

    Hammaad 
    ibn Zayd said: He used to mix up hadeeths. Shu‘bah stated that he was 
    confused. Ahmad said: He is nothing. Abu Zar‘ah said: He is not strong; he 
    made mistakes. Abu Haatim said: He cannot be quoted as evidence. 
    Ad-Daaraqutni said: In my view there is still some weakness in him

    End quote 
    from al-Mughni fi ad-Du‘afa’ by adh-Dhahabi (2/447) 

    2.
    
    Hajjaaj 
    ibn Sinaan 

    Al-Azdi 
    said concerning him: He is matrook (rejected). See: Lisaan al-Mizaan 
    by Ibn Hajar (2/563). 

    3.
    
    ‘Awn ibn 
    ‘Umaarah al-Qaysi 

    Abu Zar‘ah 
    said: His hadeeth is odd. Al-Haakim said: I met him but I did not write down 
    anything from him, and his hadeeth was odd and he was weak in narrating 
    hadeeth. Abu Dawood said: He is da‘eef.

    End quote 
    from Tahdheeb at-Tahdheeb (8/173). 

    Among the 
    imams (leading scholars) who classed the hadeeth as da‘eef were: 
    ad-Daaraqutni; al-Haafiz ibn Hajar in Nataa’ij al-Afkaar (5/56)’ 
    as-Sakhkhaawi in al-Qawl al-Badee‘ (p.284); al-Mannaawi in Fayd 
    al-Qadeer (4/249); al-Hoot al-Beiruti in Asna al-Mataalib (p. 
    175); Shaykh al-Albaani in al-Silsilah ad-Da‘eefah (8/274). 

    There is a 
    corroborating report for the hadeeth in the hadeeth of Anas ibn Maalik, who 
    said: I was standing in front of the Messenger of Allah (blessings and peace 
    of Allah be upon him) and he said: “Whoever sends blessings upon me on 
    Friday eighty times, Allah will forgive him the sins of eighty years.” It 
    was said: How may we send blessings upon you, O Messenger of Allah? He said: 
    “Say: ‘O Allah, send blessings upon Muhammad, Your slave, Your Messenger and 
    Your Prophet, the unlettered Prophet’ and count it as one.”

    Narrated 
    by al-Khateeb al-Baghdaadi in Tareekh Baghdad (13/464). Its isnaad 
    includes Wahb ibn Dawood ibn Sulaymeen ad-Dareer.

    
    Adh-Dhahabi said: al-Khateeb said: He was not trustworthy. Then he mentioned 
    a hadeeth fabricated by him. 

    End quote 
    from al-Mughni fi ad-Du‘afa’ (2/727) 

    Something 
    similar was mentioned by Ibn al-Jawzi in al-Ahaadeeth al-Waahiyah 
    (no. 796 – where he listed very weak hadeeths). 

    Shaykh 
    al-Albaani said: He should have listed it in his other book, al-Ahaadeeth 
    al-Mawdoo‘aat (Fabricated Hadeeths). That would have been more 
    appropriate, because tThe signs of fabrication are very clear in it. The 
    saheeh hadeeths that speak of the virtue of sending blessings upon the 
    Prophet (blessings and peace of Allah be upon him) are sufficient and there 
    is no need for reports such as this. For example, the Prophet (blessings and 
    peace of Allah be upon him) said: “Whoever sends blessings upon me once, 
    Allah will send blessings upon him tenfold.” Narrated by Muslim and others. 
    End quote. Silsilat al-Ahaadeeth ad-Da‘eefah wa al-Mawdoo‘ah (1/383) 

    And Allah 
    knows best.