How can I verify the sources of the hadeeths quoted in the fatwas on the Islam Q&A website?
Question

                I have a question about the isnaads of the hadeeths that you quote on your website. I would like to know how one may research the isnaads that you quote for the hadeeths that are translated into English. For example, in your fatwa no. 70216 (“Does going to the mosque riding bring the same reward as walking?”) you quoted a hadeeth that Abu Hurayrah (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings of Allah be upon him) said: “Whoever purifies himself in his house then walks to one of the houses of Allah in order to perform one of the obligatory prayers enjoined by Allah, for every two steps he takes, one will erase a sin and the other will raise him one degree in status.” Narrated by Muslim, 666... 

Now when I try to look for hadeeth no. 666 in the electronic version of Saheeh Muslim, or even in the full translation of Saheeh Muslim (7 vols, published by Darussalam), I found that the hadeeth is different from the one that you quoted. I want to be pro-active in learning my religion by researching in the sources of Qur’an and hadeeth, to make sure that what I am learning is sound, instead of following like a flock of sheep and regarding Islam as a cultural matter only, as is the case with the majority of Muslims nowadays. Could you please explain to me what I am doing wrong, and advise me as to how I can verify the soundness of the hadeeths? May Allah reward you with good.
Praise be to Allah.
    Verifying 
    knowledge is one of the ways of the righteous early generations, and we 
    invite all readers to follow their example and adhere to their way, because 
    it is the way of protecting oneself from slipping and falling into error. If 
    the people were to follow this way, knowledge would become deeply entrenched 
    in their hearts, their knowledge would be sound, and people would focus on 
    the most important branches of knowledge. 

    Imam ash-Shawkaani 
    (may Allah have mercy on him) said: 

    Once it is 
    understood that the ordinary Muslim should ask the scholar, and the one who 
    is lacking in knowledge should ask the one who has acquired a high level of 
    knowledge, then he should ask people of knowledge who are known for their 
    religious commitment and piety, as well as deep knowledge of the Qur’an and 
    Sunnah, and is well versed in both, along with knowledge of other fields 
    that help him to understand the Qur’an and Sunnah. Then he can put his 
    question to him, asking him to quote to him whatever in the Book of Allah 
    and the Sunnah of His Messenger (blessings and peace of Allah be upon him) 
    contains an answer to his problem. Then in that case he will be able to get 
    a true answer from the source (i.e., Qur’an and Sunnah) and learn the ruling 
    on the right basis. Thus he will have no need for any other views which, if 
    he followed them, he could not be sure that he will not fall into error that 
    is contrary to sharee‘ah and is different from the true answer. Whoever 
    follows this methodology will be able to get what he wants and find someone 
    to guide him to the truth.

    End quote. 
    Irshaad al-Fuhool, 2/250 

    If the reader of 
    our website wants to verify the soundness of the information mentioned in 
    the fatwas, he has two ways of doing so: 

    1.

    He may refer to 
    Islamic programs that contain texts of Islamic knowledge; with these 
    programs, he can enter part of the text quoted in the fatwa, whether the 
    text is a hadeeth or a report or the words of one of the scholars. If the 
    program contains the book quoted from, the result will appear, in sha Allah. 
    Undoubtedly this way is easiest for the researcher and is the quickest way 
    of getting results, and is readily available to all researchers. 

    2.

    The second way is 
    referring to books and printed sources. This is also very useful for the 
    reader, as he will get used to checking the books of the scholars against 
    one another, and he will get to know them in a real way. But this is a way 
    that requires more effort and access to a large library that is rich in 
    original sources. 

    To make it easier 
    for readers to find out the sources used by our website in producing fatwas, 
    we should point out that quotations given in the fatwas come only from one 
    of the following sources: 

    1.

    The Holy Qur’an

    In all our fatwas, 
    we give the number of the verse and the name of the soorah from which it is 
    quoted.  

    2.

    Hadeeth

    In the case of 
    hadeeth, we only mention the number of the hadeeth itself, without the 
    volume or page numbers. That is because there are many editions of the books 
    of hadeeth. Although there are differences in numbering of the hadeeths, 
    these differences are less than the differences in volume and page numbers. 
    When giving the numbers of hadeeth, we base it on the most well-known 
    editions, which use the numbering given by Prof Muhammad Fu’aad ‘Abd 
    al-Baaqi (may Allah have mercy on him). 

    Saheeh Muslim: 
    numbering given by Prof Muhammad Fu’aad ‘Abd al-Baaqi (may Allah have mercy 
    on him).

    Sunan Abi 
    Dawood: 
    numbering given by Shaykh Muhammad Muhiy ad-Deen ‘Abd al-Hameed (may Allah 
    have mercy on him).

    Jaami‘ 
    at-Tirmidhi: 
    numbering given by al-‘Allaamah Ahmad Shaakir (may Allah have mercy on him).

    Sunan 
    an-Nasaa’i: 
    numbering given by Shaykh ‘Abd al-Fattaah Abu Ghuddah (may Allah have mercy 
    on him).

    Sunan Ibn 
    Maajah: 
    numbering given by Prof Muhammad Fu’aad ‘Abd al-Baaqi (may Allah have mercy 
    on him).

    Musnad Ahmad: 
    if the number of the hadeeth is given, what is meant is the numbering given 
    by Ihya’ at-Turaath. If the number of the volume and page is given, what is 
    meant is the first edition which was printed in six volumes. If the 
    quotation is from the new edition published by Mu’sasat ar-Risaalah, that is 
    clearly stated. 

    If you have on 
    your computer the hadeeth program produced by the Harf company, which is one 
    of the best and most precise computer programs covering the Sunnah, then you 
    can choose the numbering system for the hadeeths under “Options”, selecting 
    the one which matches the printed editions mentioned. If you do that, you 
    will get the correct result as we mentioned. 

    However, the most 
    effective way of searching is to search for a few words of the text in 
    question, so that you will get results more readily, even if the numbering 
    is different. 

    With regard to 
    other hadeeth books, the edition quoted from may vary from one fatwa to 
    another, because of the variation in the sources available to the 
    researchers who prepare the answers for our website, and the variation in 
    editions used. 

    Anyone who wants 
    to verify a particular hadeeth that is quoted on our website from books of 
    hadeeth other than those mentioned above may contact us, and we will inform 
    him of the edition from which the hadeeth is quoted, in sha Allah. However 
    the basic principle is that we quote from the most well-known edition of all 
    books, but that may not be clear to the non-specialist reader, so there is 
    nothing wrong with contacting us and we will explain it to him. 

    3.

    Books of the 
    scholars 

    There is also no 
    one particular edition that is used in all fatwas on our website, although 
    we have tried our utmost to quote from the best editions of the scholars’ 
    books, and those which have been most thoroughly checked. In fact, we often 
    give the name of the edition used in the text of the fatwa. But variations 
    may occur, hence we hope that anyone who wants to know the source of a 
    quotation will contact us with his question, so that we can tell him the 
    name of the edition, in sha Allah. 

    4.

    With regard to 
    quotations from other websites, in that case we give the link that will take 
    the reader to the original website from which we took the information. The 
    link usually appears beneath the quoted text. 

    5.

    We also sometimes 
    quote from the program al-Maktabah ash-Shaamilah, if we do not know of a 
    book except through this program. We will state that, if the numbering of 
    the book does not match the printed edition. 

    And Allah knows 
    best.