Question 10: What is the meaning of Imam Ali’s pbuh saying: “If the veil was revealed to me, I would not have increased in certitude”?
Answer: Let no one delude themselves into thinking that the Prince of Believers pbuh is talking about veils from the Kingdom of Heaven. How could that be as he pbuh walks in the graveyard of the city of Kufah and speaks to the dead, and he turns to Haba Al-Arni and says to him,
“If the veil was ever removed for you Haba, you would have seen them [the dead] sitting in circles conversing.” 
But rather, the Prince of Believers pbuh is talking about a veil which has concealed the Divinity from him. He is talking about a veil which if revealed to Ali pbuh, Ali pbuh would not remain, and none remains save Allah, the One the Conquerer. Ali pbuh considers the presence of this veil to be a great guilt, therefore he says,
“O lord, I have done myself injustice by considering it [myself], so it is damned if You do not forgive it.” [A part of the dua of Shaban by the Prince of Believers Ali pbuh, Bihar Al-Anwar Vol. 91 page 97]
Rather the Quran itself considers it a great guilt which does not part from a human unless the clear opening happens, and the human becomes non-existent at moments, and returns to existence at other moments; this is in order for the human to maintain his humanity, and for the created to maintain his place as a servant. Allah swt said,
“We have bestowed upon you a clear opening so that Allah For- gives the guilt of your past and future.” [The Quran 48:1–2]
And the guilt here is the “I”, or the defect of darkness, which does not part from a human. And Muhammad pbuhap, due to this clear opening, was fluttering. At a time, Muhammad pbuhap would no longer remain, and none remains save Allah, the One the Conquerer. And at another time, Muhammad pbuhap returns as the first servant, the first light, the first intellect, and the winner of the race. May the peace and prayers of Allah be upon him. And since Ali pbuh is the door to Muhammad, and Muhammad is the man of clear opening, and at certain times no name or image remains of Muhammad, save Allah the One the Conquerer, therefore the door or Ali pbuh is touched by the Essence of Allah, and he is in the rank of the man of clear opening. This is why Ali pbuh said,
“If the veil was revealed for me, I would not have increased in certitude.” [Al-Manaqeb by Ibn Shahr Ashwab 1 page 317.]
The Allegories – volume 1
 Haba Al-Arni said, “I went out with the Prince of Believers so he stood in the valley of Al-Salam as if he was addressing people, so I got up when he got up, until I got tired, then I sat until I got bored, then I got up until I got tired again, and then I sat until I was bored, so I got up and collected my robe, and I said, ‘O Prince of Believers, I have felt pity for you that you are standing for so long, so take an hour of rest,’ and I spread my robe on the ground for him to sit on it, so he pbuh said, ‘O Haba, it is only a conversation with a believer or keeping his ’ So I said, ‘Are they really so?’ He said, ‘Yes, if it was revealed to you, you would have seen them in circles conversing.’ I asked, ‘Are they bodies or souls?’ He said, ‘Souls, and no believer would die in any spot of the earth without it being said to his soul, ‘Go to the valley of Al-Salam, it is a spot from the heaven of Eden.’’” Bihar Al-Anwar Vol. 97 page 234.