Sportsmen greeting one another with a bow
Question

                In some sports, such as karate, the sportsmen greet one another by bowing. Is this permissible? Please note that some of the sportsmen may be kaafirs.
Praise be to Allah.
    It is not permissible to bow to anyone when greeting them, 
    whether in the context of sports or otherwise. The Prophet (blessings and 
    peace of Allaah be upon him) forbade that. 

    Al-Tirmidhi (2728) narrated that Anas ibn Maalik (may Allaah 
    be pleased with him) said: A man said: O Messenger of Allaah, when one of us 
    meets his brother or friend, should he bow to him? He said: “No.” He said: 
    Should he embrace him and kiss him? He said: “No.” He said: Should he shake 
    hands with him? He said: “Yes.” Classed as hasan by al-Albaani in Saheeh 
    al-Tirmidhi. 

    Al-Mubaarakfoori said in Tuhfat al-Ahwadhi: 

    Bowing means tilting or inclining the head and back. 

    “He said: ‘No’” because it is the same as rukoo’ (bowing), 
    which like sujood (prostration) is an act of worship before Allaah, may He 
    be glorified. 

    “Should he embrace him” i.e., hug him and clasp him to 
    himself, “and kiss him. He said: ‘No.’” End quote. 

    The scholars of the Standing Committee for Issuing Fatwas 
    were asked: We joined a karate club in America and the trainer said that you 
    have to bow when he bows to you. We refused and explained to him that this 
    is against our religion, and he accepted that but he said that we should 
    tilt our heads only, because he is the one who bows first and it is 
    essential to return his greeting.  What is your opinion on that? 

    They replied: It is not permissible to bow in greeting to a 
    Muslim or to a kaafir, whether that involves the upper part of the body or 
    the head, because bowing is a kind of worship, and worship is only for 
    Allaah alone. 

    And Allaah is the source of strength. May Allaah sent 
    blessings and peace upon our Prophet Muhammad and his family and 
    Companions. 

    Shaykh ‘Abd al-‘Azeez ibn ‘Abd-Allaah ibn Baaz, Shaykh ‘Abd al-Razzaaq ‘Afeefu, Shaykh ‘Abd-Allaah ibn Ghadyaan, Shaykh ‘Abd-Allaah ibn Qa’ood