Hadith very diffult to understand!

[Bihar Al-Anwar 37:233; Khisaal Al-Sadouq 208; Tafsir Furat Al-Kufi 6; Maani Al-Akhbar 189]

Abul Husain bin Abi Tayyeb bin Shuaib, from Ahmad bin Qasem Al-Hashimi, from Isa, from Farroukh bin Farwah, from Mos'edah bin Sadaqa, from Saleh bin Maitham, from his father Maitham Al-Tammar, who said:
I was in the marketplace and Asbagh bin Nobatah came to me and said, 'O Maitham, I heard a very difficult hadith from the Commander of the Believers (as) today. How can that be?'
'What did you hear' I asked
Asbagh replied, 'I heard the Commander of the Believers (as) say, 'Our Ahadith are very difficult and complex. Only the high-ranked angels, the messengers, and those slaves whose hearts have been tested can handle them.'
So I (Maitham) immediately left the marketplace and went to the Commander of the Believers (as).


'O Commander of the Believers! Asbagh narrated a hadith from you today that was very difficult for me.' I said
'Which hadith was it' he asked.
I narrated the hadith that I had heard from Asbagh. The Commander of the Believers (as) smiled and asked me to sit down.
Then he said:
'Can all knowledge be handled by everyone? 'And when your Lord said to the angels, I am going to place in the earth a khalif, they said: What! wilt Thou place in it such as shall make mischief in it and shed blood, and we celebrate Thy praise and extol Thy holiness? He said: Surely I know what you do not know.'
So Could the angels handle the knowledge?'
I (Maitham) said, 'This is even greater than what I heard from Asbagh.'
The Commander of the Believers (as) said,
'Allah sent the Torah to Musa. Therefore Musa thought there was no one more knowledgeable than him.
To ensure that pride does not enter the heart of Musa, Allah said to him, 'There is someone in My creation who is more knowledgeable than you are.'
So Musa asked Allah to guide him to the most knowledgeable person, and Allah led him to Khizr. When Khizr destroyed the ship, Musa could not handle it; when Khizr killed the boy, Musa could not handle it; when Khizr built the wall, Musa could not handle it (Quran 18:65-82).
As for the believers, the Messenger of Allah (saw) held my hand on the Day of Ghadeer and said, 'O Allah! of whomsoever I am his master, this Ali is his master.'
Do you think everyone could handle that? Only those whom Allah has protected (could handle it).
Therefore rejoice and be delighted because Allah has chosen you to handle the matters and the knowledge of the Messenger of Allah (saw), and this was not entrusted to all of the angels, nor was it given to every Prophet or Messenger.'