A man mistreated his mother and he said bad words about him
Question

                If someone has badly treated with my mother,and when i got to know about it,i said bad words for that man because of his this action;is this backbitting(gheeba)?.
Praise be to Allah.
    The Prophet  (peace and blessings of Allaah be upon him) 
    described gheebah (backbiting) as being “Your mentioning about your brother 
    something that he dislikes.” If the quality that is disliked is not actually 
    present, then it is a lie, and both of them are haraam. 

    Muslim (2589) narrated from Abu Hurayrah that the Messenger 
    of Allaah  (peace and blessings of Allaah be upon him) said: “Do you 
    know what backbiting is?” They said: Allaah and His Messenger know best. He 
    said: “When you say about your brother something that he dislikes.” They 
    said: What if what I say about my brother is true? He said: “If it is true 
    then you have backbitten about him and if it is not true then you have told 
    a grave lie about him.” 

    Based on this, your saying bad things about this person in 
    his absence must be either backbiting or lying, so what you have to do is 
    repent to Allaah and resolve not to do this again. Part of repenting fully 
    is striving to correct your feelings towards him, praying for forgiveness 
    for him and mentioning his good qualities before those in whose presence you 
    spoke ill of him. See the answer to question no. 
    52807. 

    This applies if the words were said in his absence. But if 
    they were said in his presence, then this comes under the heading of 
    reviling, insulting and rudeness, which is also haraam, so long as there was 
    no retaliation, i.e., responding to bad words in kind without overstepping 
    the mark. 

    That is because Allaah says (interpretation of the meaning): 

    “The recompense for an evil is an evil like thereof; but 
    whoever forgives and makes reconciliation, his reward is with Allaah. 
    Verily, He likes not the Zaalimoon (oppressors, polytheists, and 
    wrongdoers).

    41. And indeed whosoever takes revenge after he has 
    suffered wrong, for such there is no way (of blame) against them.

    42. The way (of blame) is only against those who oppress 
    men and rebel in the earth without justification; for such there will be a 
    painful torment.

    43. And verily, whosoever shows patience and forgives, 
    that would truly be from the things recommended by Allaah”

    [al-Shoora 42:40-43]

    And Muslim (2587) narrated from Abu Hurayrah that the Prophet 
     (peace and blessings of Allaah be upon him) said: “When two people 
    revile one another, the one who starts it is the sinner, so long as the one 
    who is wronged does not overstep the mark.”  

    It says in Subul al-Salaam (2/675): The hadeeth 
    indicates that it is permissible to respond in kind to the one who insulted 
    one first, and that the sin of that will come back on the one who started 
    it, because he is the cause of everything that the one who is answering back 
    says, unless the one who is answering back oversteps the mark, in which case 
    the sin of aggression is borne by him, because the permission is granted to 
    respond only to the same extent as the initial offence: 
    “The recompense for an evil is an evil like thereof” 
    [al-Shoora 42:4] and “Then whoever transgresses the prohibition against you, 
    you transgress likewise against him” [al-Baqarah 2:194].

    But not responding in kind, being patient and putting up with 
    it is better. It is proven that a man reviled Abu Bakr (may Allaah be 
    pleased with him) in the presence of the Prophet  (peace and blessings 
    of Allaah be upon him) and Abu Bakr kept quiet whilst the Prophet  
    (peace and blessings of Allaah be upon him) was sitting there. When Abu Bakr 
    responded, the Prophet  (peace and blessings of Allaah be upon him) got 
    up and left. He was asked about that and he said: “When Abu Bakr kept quiet 
    there was an angel responding on his behalf, but when he stood up for 
    himself, the shaytaan came,” or words to that effect. Allaah says 
    (interpretation of the meaning): 

    “And verily, whosoever shows patience and forgives, that 
    would truly be from the things recommended by Allaah”

    [al-Shoora 42:40-43]

    End quote. 

    But if you respond to this mistreatment by speaking and 
    acting kindly towards him, and being gentle and nice, and obey Allaah with 
    regard to him when he disobeys Him with regard to you, that is the status of 
    people of a high level of taqwa (piety), which only a few can attain.  

    Allaah says (interpretation of the meaning): 

    “The good deed and the evil deed cannot be equal. Repel 
    (the evil) with one which is better (i.e. Allaah orders the faithful 
    believers to be patient at the time of anger, and to excuse those who treat 
    them badly) then verily he, between whom and you there was enmity, (will 
    become) as though he was a close friend.

    35. But none is granted it (the above quality) except 
    those who are patient — and none is granted it except the owner of the great 
    portion (of happiness in the Hereafter, i.e., Paradise and of a high moral 
    character) in this world”

    [Fussilat 41:34-35]

    May Allaah help us and you to do that which He loves and 
    which pleases Him. 

    And Allaah knows best.