The Prophet’s seeing those who were behind his back
Question

                I believe that Allah is the only knower of the Unseen, and He is the Only one that Heals the Sick. I give Dawah to people regarding it(Tawheed), from Quran and Sunnah, as per my knowledge. I was sent 2 Ahadiths from a person negating my argument they are as follows:

"Abdullah. the freed slave of Asma' (the daughter of Abu Bakr). the maternal uncle of the son of 'Ata, reported: Asma' sent me to 'Abdullah b. 'Umar saying: The news has reached me that you prohibit the use of three things: the striped robe. saddle cloth made of red silk. and the fasting in the holy month of Rajab. 'Abdullah said to me: So far as what you say about fasting in the month of Rajab, how about one who observes continuous fasting? -and so far as what you say about the striped garment, I heard Umar b. Khatab say that he had heard from Allah's Messenger (may peace be upon him): He who wears silk garment has no share for him (in the Hereafter), and I am afraid it may not be that striped garment; and so far as the red saddle clotb is concerned that is the saddle cloth of Abdullah and it is red. I went back to Asma' and informed her. whereupon she said: Here is the cloak of Allah's Messenger (may peace be upon him). and she brought out to me that cloak made of Persian cloth with a hem of brocade, and its sleeves bordered with brocade and said: This wall Allah's Messenger's cloak with 'A'isha until she died, and when she died."

This is an important part of the same Hadith:

"I got possession of it. The Apostle of Allah (may peace be upon him) used to wear that, and we now washes it for the sick and cure them by it through its water."
Narrated in Sahih al Muslim Book 024, Number 5149.

The Second Hadith is from Bukhari, Book # 1, Page 59:
"By Allah, neither your Bowing is hidden from Me, nor your Khushu is hidden from me, and verily even I see you from my back."

I wanted to know the context and interpretation of these Ahadiths, and are they Sahih? Plus can we make them a proof for saying, Prophet of Allah cures someone and is all-Seeing?
Praise be to Allah.
    Firstly: 

    One of the Muslims’ beliefs is the belief that Allah alone is 
    the Knower of the unseen, and no one knows the unseen except Him. Allah, may 
    He be glorified, says (interpretation of the meaning):

    “Say: ‘None in the heavens and the earth knows the Ghaib 
    (unseen) except Allah, nor can they perceive when they shall be 
    resurrected.’”

    [an-Naml 27:65].

    Ibn Katheer (may Allah have mercy on him) said: 

    Here Allah, may He be exalted, instructs His Messenger 
    (blessings and peace of Allah be upon him) to say to all of creation, 
    informing them that no one knows the unseen except Allah, may He be 
    glorified and exalted, for He is the only one who has this knowledge, with 
    no partner or associate.

    End quote from Tafseer Ibn Katheer (6/207) 

    But Allah ,may He be exalted, may inform whomever He wills of 
    His Messengers of whatever He wills of the unseen. Allah, may He be exalted, 
    says (interpretation of the meaning):

    “(He Alone) the All-Knower of the Ghaib (unseen), and He 
    reveals to none His Ghaib (unseen).

    Except to a Messenger (from mankind) whom He has chosen (He 
    informs him of unseen as much as He likes), and then He makes a band of 
    watching guards (angels) to march before him and behind him”

    [al-Jinn 72:26-27].

    The scholars of the Standing Committee said: 

    The basic principle regarding matters of the unseen is that 
    they are known only to Allah, but Allah, may He be exalted, may disclose 
    matters of the unseen to whomever He wills among His Messengers. Allah, may 
    He be exalted, says (interpretation of the meaning):

    “(He Alone) the All-Knower of the Ghaib (unseen), and He 
    reveals to none His Ghaib (unseen).

    Except to a Messenger (from mankind) whom He has chosen (He 
    informs him of unseen as much as He likes), and then He makes a band of 
    watching guards (angels) to march before him and behind him”

    [al-Jinn 72:26-27].

    End quote from Fataawaa al-Lajnah ad-Daa’imah 
    (1/122-123)

    That which is disclosed to the Messenger of matters of the 
    unseen is only through revelation from Allah, may He be exalted. Hence 
    Allah, may He be glorified and exalted, says (interpretation of the 
    meaning):

    “Say (O Muhammad blessings and peace of Allah be upon him): 
    ‘I don’t tell you that with me are the treasures of Allah, nor (that) I know 
    the unseen; nor I tell you that I am an angel. I but follow what is revealed 
    to me by inspiration.’”

    [al-An‘aam 
    6:50]. 

    The scholars of the Standing Committee said: 

    Knowledge of the unseen is something that is unique to Allah, 
    may He be exalted, so none of His creation, jinn or others, knows that 
    except what Allah may reveal to whomever He wills among His angels or 
    Messengers.

    End quote from Fataawa al-Lajnah ad-Daa’imah (1/346)

     The Prophet (blessings and peace of Allah be upon him) did 
    not have knowledge of the unseen, as is the apparent meaning of the verse in 
    which Allah, may He be exalted, says (interpretation of the meaning):

    “Say (O Muhammad blessings and peace of Allah be upon him): 
    "I don’t tell you that with me are the treasures of Allah, nor (that) I know 
    the unseen”

    [al-An‘aam 6:50].

    But Allah is the Knower of the unseen, some of which which He 
    discloses to whomever He wills, as He says (interpretation of the meaning):

    “(He Alone) the All-Knower of the Ghaib (unseen), and He 
    reveals to none His Ghaib (unseen)”

    [al-Jinn 72:26]. 

    Al-Qutubi (may Allah have mercy on him) said: 

    The scholars (may Allah have mercy on them) said: as Allah, 
    may He be glorified, is praised for having knowledge of the unseen, which He 
    has kept to Himself, to the exclusion of His creation, this indicates that 
    no one has knowledge of the unseen except Him. Then He made an exception for 
    those with whom He is pleased of the Messengers, and disclosed to them 
    whatever He willed of the unseen, by means of revelation to them, which He 
    made a miracle for them and a true sign of their Prophethood.

    End quote from Tafseer al-Qurtubi (1 9/28) 

    See also the answer to question no. 
    101968

    Secondly: 

    Al-Bukhaari (418) and Muslim (424) narrated from Abu Hurayrah 
    that the Messenger of Allah (blessings and peace of Allah be upon him) said:
    

    “Do you think that I face the qiblah (and do not know what 
    you are doing)? By Allah, your bowing and prostrating are not hidden from 
    me; I can see you behind my back.” 

    An-Nawawi (may Allah have mercy on him) said: The scholars 
    said: What this means is that Allah, may He be exalted, created for the 
    Prophet (blessings and peace of Allah be upon him) the ability in the back 
    of his head to see what was behind him, and he (blessings and peace of Allah 
    be upon him) was granted more extraordinary abilities than this. This is not 
    contrary to reason or textual evidence; rather the texts confirm this, so we 
    must believe in it. End quote. 

    These are miracles and signs with which Allah supported His 
    Prophet (blessings and peace of Allah be upon him) and they were unique to 
    him. Al-Haafiz Ibn Rajab (may Allah have mercy on him) said:  

    This does not mean that he used to turn around and look 
    behind him whilst he was praying, so that he could see how they were 
    praying, as some people think. Imam Ahmad refuted those who claimed that, 
    and affirmed that this was one of his unique characteristics, and one of his 
    signs and miracles.

    End quote from Fath al-Baari by Ibn Rajab (4/341) 

    Al-Haafiz Ibn Hajar (may Allah have mercy on him) said: 

    The correct view is that it is to be interpreted as it 
    appears to mean, and that this “seeing” was in a real and literal sense that 
    was unique to the Prophet (blessings and peace of Allah be upon him) and was 
    an extraordinary feat. Based on that, the author narrated this hadeeth under 
    the heading of the signs of Prophethood; it was also narrated under a 
    similar heading from Imam Ahmad and others.

    End quote. 

    To sum up: 

    This was one of the unique characteristics 
    and miracles of the Messenger of Allah (blessings and peace of Allah be upon 
    him), but this does not contradict what we stated above about Allah being 
    the only One who has knowledge of the unseen, because we have affirmed that 
    Allah may disclose to whomever He wills among His Messengers whatever He 
    wills of matters of the unseen. Hence the Messenger knew some matters of the 
    unseen of which his Lord, may He be glorified, informed him. But what is 
    mentioned in this hadeeth has nothing to do with matters of the unseen. The 
    Messenger of Allah (blessings and peace of Allah be upon him) did not say to 
    his Companions “I know what is unseen behind my back” or “I know such and 
    such”. Rather what the Messenger of Allah (blessings and peace of Allah be 
    upon him) knew in this case was something visible and seen. The only matter 
    of note in this case is that ordinarily a person only sees what is in front 
    of him, but the Messenger (blessings and peace of Allah be upon him) in this 
    instance blessings and peace of Allah be upon him what was behind him. So it 
    was an extraordinary event, and his seeing what was behind his back is 
    confirmed even though it was something out of the ordinary. 

    And Allah knows best.