Brother, some people may have difficulty in comprehending how the Prophet [May ALLAH bless Him and His Family] could have so much power to the extent that he hazir o nazir. Firstly such a thing can never be difficult for the Prophet [May ALLAH bless Him and His Family], and secondly there is nothing to be surprised by when ALLAH grants his special servants abilities of such nature.
Hafidhh Ibn Kathir writes:
An example of this would be of the Angel Izra’eel Alaihi salaam, who at all times has the Lawh-e-Mahfooz (guarded tablet) in his sight, and it is through this he sees the whole world. He even visits every house on land and under water five times a day. [Tafsir Ibn Kathir, Surah Sajdah, under verse 11. Also in Tareek Ibn Kathir vol.1, Chapter on Lawh-e-Mahfooz]
Apart from his servants, Allah has even given power to Shaytaan, who sits on his throne in the sea and sees you wherever you may be. [Surah Al-’Araaf, under verse 27]
So if Allah can bestow such powers to a Kafir then why is it so difficult to believe that He can bestow such powers to the most beloved of his creation - Our Prophet [May Allah Bless Him and His Family]?
The evidence provided above, was to demonstrate that the Prophet [May Allah bless Him and His Family] is a witness over the whole of his Ummah - and this is what is meant by Hadhir/Nadhir.
ALSO.....
ALLAH [Glorified & Exalted] says in the Qur’an
"O Prophet! [May Allah bless Him & His Family] no doubt, We have sent you as a witness, bearer of glad tiding and a Warner"
[Surah Al-Ahzab, verse 45.]
The Qur’an refers to RasoolAllah [Peace be upon Him & His Family] as ‘Shahid’(witness) and the witness is someone who sees whilst being present. [Mufradaat, Imam Raghib, under the word Shahid]
Allah sent the Prophet [May Allah bless Him & His Family] as Shahid. It is for this reason we refer to him as metaphorically being Haadhir/Nadhir and that he is not Hadhir/Nadhir in the way that are the Angels Kiraman, Katibeen. (The Angels who are constantly present on the right and left shoulder of every human being.)
I hope you accept the truth abouth The powers recieved from ALLAH [Glorified & Exalted] by The Our Beloved Holy Prophet [Peace be upon Him & His Family].