Soundness of the Hadeeth “Whoever persists in saying the first takbeer at the beginning of Fajr prayer for forty days…”?
Question

                Is there a hadeeth which says that one who persists in saying the first takbeer (saying Allahu Akbar) at the beginning of Fajr prayer for forty days will be free of kufr (disbelief) and hypocrisy?
Praise be to Allah.
    In Shu’ab 
    al-Eeman by al-Bayhaqi there is a marfoo’ hadeeth (report) narrated from 
    Anas ibn Malik (may Allah be pleased with him) according to which the 
    Prophet (peace and blessings of Allah be upon him) said: “Whoever prays Fajr 
    and ‘Isha in congregation and does not miss one rak’ah, he will be recorded 
    as being free from two things: free from the Fire and free from 
    hypocrisy.” (Shu’ab al-Eeman, 3/62). 

    It says in 
    al-‘Ilal al-Mutanahiyah: This hadeeth is not saheeh (authentic) and its 
    narrators are not known apart from Bakr ibn Ahmad narrating from Ya’qoob ibn 
    Tahiyyah, both of whose condition is unknown. (1/432).  

    But a 
    different version was narrated in Sunan al-Tirmithi, where it says: “Whoever 
    prays to Allah for forty days in congregation, catching up with the first 
    takbeer, he will be recorded as being free from two things: free from the 
    Fire and free from hypocrisy.” (al-Tirmithi no. 241; classed as da’eef by 
    al-Tirmithi but as hasan/sound by al-Albani). 

    This 
    hadeeth was also classed as da’eef by a number of earlier scholars, who 
    stated that it is mursal (chain does not reach the Companions), but it was 
    classed as hasan by some of the later scholars. See Talkhees al-Habeer, 
    2/27. 

    The 
    hadeeth is not limited to Fajr prayer only, rather the reward mentioned in 
    the hadeeth is connected to being present for the opening takbeer of all the 
    five daily prayers. 

    
    Undoubtedly being keen to catch up with the opening takbeer for this period 
    of time is an indication of the strength of a person’s religious 
    commitment. 

    So long as 
    the hadeeth can be interpreted in a sound manner, there is the hope that the 
    one who is keen to do what is mentioned therein will attain this great 
    virtue. The least that he will attain by means of this keenness is training 
    himself to regularly observe this important rite of Islam. 

    We ask 
    Allah to write for us and for you freedom from hypocrisy and from the Fire, 
    for He is the All-Hearing, Ever-Responsive.