He swore a false oath so that his friend would take his charity and not reject it
Question

                I have done something which I am a bit confused about and unsure if it was right. I wanted to give someone I know very closely a sadaqa because I knew this person is very desperate for help but is unwilling to seek it from others. I gave it to this person secretively because if this person found out it was me they would be really upset (and sadaqa is preferred to be secretive anyways).

I understand lying is haraam, but permissible in 3 cases, one of them being a case in which you are trying to reconcile and make peace between others.

In this situation, the person received the sadaqa in the mail, and approached me about it, believing it was sent by me. Had I told the person it was really me, they would have rejected the sadaqa, and would have been upset because they would have thought I was pitying them (again this person does not like requesting help from others at all). I did not intend to make them feel bad nor did I want them to feel in anyway inferior and so I sent it anonymously.

However in keeping with this, when the person approached me I lied to them and told them it was not me. Was this a wrong action? Should I not have lied in this situation?

Also the person asked me to say "Wallah" which I know is a very serious matter. If my lying was permissible in this case, was swearing by Allah a grave sin?

Please let me know, this has really been concerning me! JazakaAllahu khairan.
Praise be to Allah.
    Firstly: 

    What you did of sending the charity to this man and 
    concealing it, and being keen to make sure that it reached him, was a good 
    deed and we ask Allah to reward you for it in the best way. But you made a 
    mistake when you swore a false oath. What you have to do is repent to Allah, 
    may He be exalted, from that, because you could have used a 
    double-entendre. 

    Double-entendre means saying something that appears to mean 
    one thing that is understood by the listener, but the speaker intends 
    something else that may be understood from the words. For example you could 
    have said, “I did not send money to you,” meaning that you did not send 
    money to him a month ago, or you did not send it to him today. This is 
    permissible if necessary or if it serves a legitimate shar‘i purpose. 

    Al-Nawawi (may Allah have mercy on him) said: The scholars 
    said: If there is a clear legitimate shar‘i purpose that will be served by 
    deceiving the person you are speaking to, or if there is a need for it that 
    can not be met except by lying, then there is nothing wrong with using a 
    double-entendre. But if there is no purpose to be served and no need for it, 
    then it is makrooh, but it is not haraam. If it is used as a means to take 
    something unlawfully or avoid paying one’s dues, then in that case it is 
    haraam. This is the guideline to be followed in this issue. End quote from
    al-Adhkaar, p. 380 

    See also question no.
    27261 

    Secondly: 

    Some scholars granted a concession allowing lying when there 
    is a clear interest to be served by doing so. 

    Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allah have mercy on him) 
    said: What is prescribed for the believer is to refrain from swearing oaths 
    even if they are sincere, because swearing oaths frequently may lead to 
    telling lies, and it is well known that lying is haraam, and if the lie is 
    accompanied by an oath, it is even more haraam. But if it is necessary or 
    there is an interest to be served by swearing a false oath, there is nothing 
    wrong with that, because of the report narrated from the Prophet (blessings 
    and peace of Allah be upon him) in the hadeeth of Umm Kulthoom bint ‘Uqbah 
    ibn Abi Mu‘eet (may Allah be pleased with him), according to which the 
    Prophet (blessings and peace of Allah be upon him) said: “He is not lying 
    who reconciles between people, transmitting good words and saying good 
    things.” She said: And I did not hear him grant any concession allowing any 
    of that which people call lying except in three cases: reconciling between 
    people, war, and what a man says to his wife or a wife says to her husband. 
    Narrated by Muslim in al-Saheeh. If a person says when reconciling 
    between people: By Allah, your friends want to reconcile and they want to 
    come to an agreement,  and so on, then he goes to the others and says 
    something similar, with a good intention and seeking to bring about 
    reconciliation, there is nothing wrong with that. 

    Similarly, if he sees someone who wants to kill another 
    person wrongfully, or to wrong him in some other way, and he says to him: By 
    Allah, he is my brother, so as to save him from this wrongdoer who wants to 
    kill him unlawfully or to beat him unlawfully, and he knows that if he says 
    he is his brother he will leave him alone out of respect for him, then he is 
    obliged to do something like this in order to serve this purpose and save 
    his brother from wrongdoing. 

    The point is that the basic principle with regard to false 
    oaths is that they are not allowed and are haraam, unless it serves a 
    greater purpose that outweighs the lie, as in the three cases mentioned in 
    the hadeeth quoted above.

    End quote from Majmoo‘ Fataawa al-Shaykh Ibn Baaz, 
    1/54 

    But using a double-entendre is recommended and avoids the 
    problem of lying, as stated above. 

    And Allah knows best.