Translation:

27. "Except an apostle whom He has chosen: and then He makes a band of watchers march before him and behind him

Notes (Tafseer)

5750. Cf. iii. 179, and n. 482. See also last note.

5751. Revelation is not a mechanical or material thing. It has to be safeguarded from being distorted or corrupted by ignorance, selfishness, or the powers of evil. How can its precious and subtle worth and the spiritual safeguards against its misuse by human folly or the perversity of evil be expressed in plain human words? We can imagine a very great treasure, which has to be transmitted. To guard it against evilly-disposed persons, a strong escort is required, to march in front and behind, so as to protect it from all sides. When it reaches its destination, the escort presents its credentials and an Invoice showing the Treasure being transmitted. Then the destined receiver knows that it has come intact and feels satisfied. So about spiritual Revelation. The Prophet recognises the credentials and checks the contents on the tablets of his own heart and insight. He has then no doubt that it is a true Message from Allah, and that those who bring it are the true messengers "of their Lord". A) They: the band of watchers. In "he may know" it is better to construe "he" to refer to the prophet who receives the Message from the "watchers".