What is the evidence for looking the place of prostration when bowing in rukoo’?
Question

                We have read a fatwa from the Standing Committee for Academic Research and Issuing Fatwas – which appears in question no. 8580 – which states that the worshipper should look at the place of prostration whilst bowing. Is there any evidence for this opinion?.
Praise be to Allah.
    Firstly: 

    There are ahaadeeth among the saheeh Sunnahs which mention 
    the teaching of the Prophet  (peace and blessings of Allaah be upon him) 
    concerning looking at the place of prostration during prayer. These, in 
    general, include all the parts of the prayer, and perhaps these texts are 
    the ones that were quoted by the scholars of the Standing Committee and 
    quoted by them in the answer to question no. 
    8580. These texts include the 
    following: 

    Ibn Hibbaan (4/332) and al-Haakim (1/625) narrated that 
    ‘Aa’ishah said: “The Messenger of Allaah  (peace and blessings of Allaah 
    be upon him) entered the Ka’bah and his gaze did not go beyond the site of 
    his prostration until he came out.” Classed as saheeh by al-Albaani in 
    Sifat Salaah al-Nabi  (peace and blessings of Allaah be upon him). 

    With regard to the reports of some of the salaf that were 
    quoted by ‘Abd al-Razaaq al-San’aani in al-Musannaf, these include 
    the following: 

    1 – It was narrated that Abu Qalaabah said: I asked Muslim 
    ibn Yassaar where should my gaze fall whilst I am praying? He said: If it 
    falls where you prostrate, that is good. 

    2 – It was narrated that Ibraaheem al-Nakha’i used to like 
    for the worshipper not to let his gaze wander beyond the place of 
    prostration. 

    3 – It was narrated that Ibn Sireen used to like for a man to 
    focus his gaze on the place of prostration. 

    Musannaf ‘Abd al-Razzaaq, 2/163 

    This is what the scholars of the Standing Committee said is 
    the view of the majority: Abu Haneefah, al-Shaafa’i and Ahmad. Some of them 
    made an exception in the case of the tashahhud, when the worshipper should 
    look at his finger. This is a sound exception, supported by reports in the 
    saheeh Sunnah. 

    It was narrated from ‘Abd-Allaah ibn al-Zubayr that when the 
    Prophet  (peace and blessings of Allaah be upon him) “sat for the 
    Tashahhud, he would place his left hand on his left thigh and point with his 
    index finger, and would not let his gaze go beyond his finger.”  

    Narrated by Abu Dawood, 990; al-Nasaa’i, 1275; classed as 
    saheeh by al-Nawawi in Sharh Muslim. 5/81. He said: The Sunnah is not 
    to let one's gaze go beyond the pointing (finger). There is a saheeh hadeeth 
    concerning this in Sunan Abi Dawood.  

    Some of the scholars interpreted the verse in which Allaah 
    says (interpretation of the meaning): 

    “so turn your face in the direction of Al-Masjid Al-Haraam 
    (at Makkah)”

    [al-Baqarah 2:144]

    as meaning that the worshipper should look straight ahead, 
    not at the place where he prostrates, but this is a less correct view. 

    Ibn Qudaamah said:  

    It is mustahabb for the worshipper to fix his gaze on the 
    place of prostration. Ahmad said – according to the report of Hanbal – : 
    Proper focus and humility (khushoo’) in prayer means that (the worshipper) 
    should fix his gaze on the place of prostration, this was narrated from 
    Muslim ibn Yasaar and Qataadah. 

    Al-Mughni, 1/370 

    Secondly: 

    In the saheeh Sunnah it is narrated that when the worshipper 
    bows, it is mustahabb for him not to raise his head or his gaze, rather they 
    should be level with his back. It was narrated that ‘Aa’ishah said: The 
    Messenger of Allaah  (peace and blessings of Allaah be upon him) used to 
    start his prayer with takbeer (saying Allaahu akbar), then he would recite
    al-hamdu Lillaahi Rabb il-‘Aalameen (i.e., al-Faatihah), and when he 
    bowed he would not raise or lower his head, rather it was somewhere between 
    the two.”  

    Narrated by Muslim, 498. 

    Shaykh Ibn ‘Uthaymeen said, when he was explaining how rukoo’ 
    is to be done, that it is mustahabb for the person who is bowing to keep his 
    back in a straight line. 

    He said: With his back straight means that his back should be 
    kept straight throughout, when going down and when coming up; he should not 
    arch his back, or bend it in such a way that the middle comes down. Rather 
    his back should be straight. This is what has been narrated from the Prophet 
     (peace and blessings of Allaah be upon him). ‘Aa’ishah said: “When he 
    bowed, he did not either raise or lower his head,” – i.e., it was somewhere 
    in between the two. 

    Al-Sharh al-Mumti’, 3/90.