Can he propose to a woman whom his friend saw before and decided not to marry?
Question

                I am a young single man. Is it permissible for me to propose marriage to a woman to whom one of my friends proposed marriage and saw her, but then rejected her?

 If I propose to her and marry her, will my marriage contract be in accordance with Islamic sharee’ah, or will my marriage be faulty because my friend looked at her?.
Praise be to Allah.
    If this woman is of good character and is religiously 
    committed, there is nothing wrong with proposing marriage to her. Women may 
    be seen by more than one suitor before they get married to one of them. The 
    mere fact that your friend looked at her does not mean that you cannot marry 
    her. Even if she was married before, then she was divorced or her husband 
    died, which is more serious than looking, would anyone hesitate to say that 
    it is permissible to marry her? 

    There are clear saheeh texts which speak of the matter about 
    which you are asking, such as the following: 

    It was narrated that Ibn ‘Umar (may Allaah be pleased with 
    him) said: The Prophet  (peace and blessings of Allaah be upon him) 
    forbade outbidding one another, and no man should propose to a woman to whom 
    his brother has already proposed, unless the first suitor gives up the idea 
    or gives him permission to propose. 

    Narrated by al-Bukhaari, 4848; Muslim, 1412 

    This hadeeth shows that it is haraam to propose to a woman to 
    whom someone else has already proposed, and that it is not permissible for 
    the second suitor to propose unless the first suitor withdraws his proposal 
    or gives permission to the second. This is what has happened with you and 
    your friend. 

    If you are sure that she is of good character and religiously 
    committed, then you should pray istikhaarah, then propose to her. 

    We ask Allaah to help you to do that which is best for you.  

    And Allaah knows best.