Nun. By the Pen and by the (Record) which (men) write 5592 5593
Nun is an Abbreviated Letter: see Appendix I at the end of S. ii. Nun may mean a fish, or an ink-holder, or it may be just the Arabic letter of the alphabet, N. In the last case, it may refer to either or both of the other meanings. Note also that the Arabic rhyme in this Sura ends in N. The reference to ink would be an appropriate link with the Pen in verse 1. The reference to the fish would be appropriate with reference to the story of Jonah in verses 48-50. Jonah's title is "the Companion of the Fish", (Zun-Nun, xxi. 87), as he was, in the story, swallowed by the Fish.
The Pen and the Record are the symbolical foundations of the Revelation to man. The adjuration by the Pen disposes of the flippant charge that Allah's Messenger was mad or possessed. For he spoke words of power, not incoherent, but full of meaning, and through the Record of the Pen, that meaning unfolds itself, in innumerable aspects to countless generations. Muhammad was the living Grace and Mercy of Allah, and his very nature exalted him above abuse and persecution.