Translation:

51. It is not fitting for a man that Allah should speak to him except by inspiration of from behind a veil or by the sending of a Messenger to reveal with Allah's permission what Allah wills: for He is Most High Most Wise.

Notes (Tafseer)

4597. This leads us on to the higher spiritual meaning of verses 49-50, as leading up to verses 51-53. Man is but a speck in Allah's creation. His growth and family relationships are not by any means comparable to Allah's creative acts, whose various stages are referred to in n. 120 to ii. 117, n. 916 to vi. 94, and n. 923 to vi. 98. That being so in the mysteries of man's daily life, how much more profound is the contrast between man and Allah in the apprehension of the higher spiritual problems concerned with Revelation? How can man be fit to speak to Allah? He is not fit. But there are three ways in which Allah, in His infinite Mercy, communicates with man, as described in verses 51-53.

4598. Allah is Most High, Most Wise: man is, in spite of his high destiny, often the lowest of the low (xcv. 5). Yet Allah, out of His infinite Mercy and Grace, has bestowed His revelation on man. How does it come about? Three ways are mentioned: (1) Wahyun, Inspiration; (2) from behind a veil; and (3) by the sending of a Messenger: see the notes following. Wahyun, Inspiration, is interpreted to be of two kinds: (1) a suggestion thrown by Allah into the heart or mind of man, by which man understands the substance of the Message, whether it is a command or prohibition, or an explanation of a great truth; and (2) verbal or literal inspiration, by which the actual words of Allah are conveyed in human language.

4599. Behind a veil: not of course a material veil, but the veil of Light. Muslim relates a tradition that the Prophet said: "His veil is Light: were He to withdraw it, then would the august splendours of His countenance surely consume everything that comes within His Sight."

4600. Messenger: Rasul: the angel Gabriel, through whom the revelations were given to the holy Prophet.