Ruling on swearing a false oath in order to reconcile between people
Question

                What is the ruling on one who swears an oath when reconciling between two parties, then breaks the oath?.
Praise be to Allah.
      This question is rather ambiguous but may be discussed as 
      follows. 

    If he said, “By Allah, I will do such and such,” or “By 
    Allah, I will help you to do such and such,” or “By Allah, he did not do 
    such and such” -- and he did that for the purpose of reconciliation, then if 
    he swore an oath for the purpose of reconciliation in a way that did not 
    harm anyone, there is nothing wrong with it. [So he could say:] “By Allah, 
    So and so said such and such about you… By Allah, such and such a group 
    praised you and thanked you and say that you are their friend,” in order to 
    bring about reconciliation between them. 

    But if he said, “By Allah, I will visit you, or I will help 
    you with something if you reconcile, and stop this dispute,” then in this 
    case he has to fulfil what he promised them, because promises are important 
    and one of the characteristics of the believer is that he fulfils his 
    promises. Allah said concerning Ismaa‘eel (interpretation of the meaning):

    “And mention in the Book (the Qur’ân) Ismâ‘îl (Ishmael). 
    Verily, he was true to what he promised, and he was a Messenger, (and) a 
    Prophet”

    [Maryam 19:54].  

    He should not break his promise, because breaking a promise 
    is one of the characteristics of the hypocrites, and when a hypocrite makes 
    a promise, he breaks it. He has to offer expiation if he did break his 
    promise, even though he acquired one of the characteristics of the 
    hypocrites by breaking his promise. He still has to offer kafaarat yameen 
    (expiation for breaking an oath), because he said, “By Allah, I will visit 
    you on such and such a day,” or “By Allaah, I will help you,” but he did not 
    do that, so he has to face the consequences and he may be sinning according 
    to those who say that it is obligatory to fulfil oaths based on the apparent 
    meaning of the evidence. Or he may not be sinning, but he has acquired one 
    of the characteristics of the hypocrites that he should not have acquired. 

    The apparent meaning of the shar‘i evidence is that 
    fulfilling promises is something obligatory, and that breaking them is 
    something haraam and is one of the characteristics of the hypocrites. It is 
    not appropriate for one who seeks to bring about reconciliation to break his 
    promise, because this will affect future attempts at reconciliation. So he 
    should never break his promise; rather he should keep his promise and strive 
    hard to do that. 

    This also applies to other oaths that are sworn falsely in 
    order to bring about reconciliation and which do not harm anyone. There is 
    nothing wrong with doing that for this purpose of reconciliation, because of 
    the apparent meaning of the saheeh hadeeth narrated from Umm Kulthoom bint 
    ‘Uqbah ibn Abi Ma‘eet who said: I heard the Messenger of Allah (blessings 
    and peace of Allah be upon him) say: “He is not a liar who reconciles 
    between people and conveys something good or says something good.” She said: 
    I never heard him allowing a concession for any kind of lying except in 
    three cases: when reconciling between people, during war, and when a man 
    speaks to his wife or a woman speaks to her husband. 

    Lying which does not harm people is permissible in cases of 
    reconciliation, but it should benefit the people among whom reconciliation 
    is sought, and it should not harm anyone else. End quote. 

    Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allah have mercy on him)