Taking back charity before the recipient takes possession of it
Question

                I had intended to give some money to someone because he needed it, but I changed my mind because of an emergency which meant that I needed it. Please note that I did not tell him about that. What is the ruling on this?.
Praise be to Allah.
      Firstly: 

    The questioner is surely aware of the virtue of giving 
    charity and what Allah has prepared for those who are charitable. Allah, may 
    He be exalted, says (interpretation of the meaning):

    “Verily, those who give Sadaqaat (i.e. Zakaah and alms), 
    men and women, and lend Allaah a goodly loan, it shall be increased manifold 
    (to their credit), and theirs shall be an honourable good reward (i.e. 
    Paradise)”

    [al-Hadeed 57:18]

    “Those who spend their wealth (in Allaah’s Cause) by night 
    and day, in secret and in public, they shall have their reward with their 
    Lord. On them shall be no fear, nor shall they grieve”

    [al-Baqarah 2:274]. 

    There are many verses and hadeeths which speak of the virtue 
    of giving charity; you may see some of them in the answer to question no.
    36783. 

    Secondly: 

    There is nothing wrong with taking back charity before it is 
    handed over to the poor person or to his deputy, because charity does not 
    become the poor person’s property until it is handed over to him. If it has 
    not been handed over to him then it is still the property of the giver, 
    because Allah, may He be exalted, says (interpretation of the meaning):

    “If you disclose your Sadaqaat (almsgiving), it is well; 
    but if you conceal them and give them to the poor, that is better for you”

    [al-Baqarah 2:271]. 

    Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said in 
    his commentary: One of the things that we learn from this verse is that 
    charity is not regarded as such until it actually reaches the poor person, 
    because Allah, may He be exalted, says: “and give them to the poor”. 

    Imam Ahmad (26732) narrated that Umm Kulthoom bint Abi 
    Salamah said: When the Messenger of Allah (blessings and peace of Allah be 
    upon him) married Umm Salamah, he said to her: I had given to the Negus a 
    hullah suit and some ounces of musk, but I think that the Negus has died, 
    and I think that my gift will be returned to me; if it is returned to me, 
    then it is yours…” al-Haafiz said in Fath al-Baari: Its isnaad is 
    hasan. 

    It says in Daqaa’iq Ooli’l-Nuha (1/468): If a person 
    earmarks something to give in charity or delegates someone to give it, then 
    he decides that he will not give it in charity, it is better for him to go 
    ahead with it, so as to go against his greed and the whisper of the 
    Shaytaan, but he is not obliged to go ahead with it because it does not 
    change possession before it is handed over. End quote. 

    This is the view of most of the fuqaha’. See al-Mughni, 
    5/379, 383 

    But after he has handed it over himself or through his 
    deputy, it is not permissible for him to take it back according to the 
    consensus of the scholars (may Allah have mercy on them), because of the 
    report narrated by al-Bukhaari in his Saheeh (2589) from Ibn ‘Abbaas 
    (may Allah be pleased with him), according to which the Prophet (blessings 
    and peace of Allah be upon him) said: “The one who takes back his gift is 
    like the dog that vomits then goes back to its vomit.” According to another 
    version (2623), “the one who takes back his charity.” 

    Maalik narrated in al-Muwatta’ (1477) that ‘Umar ibn 
    al-Khattab (may Allah be pleased with him) said: “Whoever gives a gift to 
    uphold ties of kinship or by way of charity should not take it back…” Its 
    isnaad was classed as saheeh by Shaykh al-Albaani (may Allah have mercy on 
    him) in Irwa’ al-Ghaleel, 6/55 

    Al-Bukhaari included a chapter in his Saheeh entitled: 
    It is not permissible for anyone to take back his gift or charity. 

    Al-Haafiz Ibn Hajar said: … With regard to charity, they are 
    unanimously agreed that it is not permissible to take it back after it has 
    been handed over. End quote from Fath al-Baari. 

    To sum up: if a person intended to give some money, then it 
    is better for him to go ahead with this act of charity, although that is not 
    obligatory, so long as he has not handed it over to the poor person. If he 
    has handed it over, then it is not permissible to take it back, according to 
    the consensus of the scholars, may Allah have mercy on them. 

    And Allah knows best.