ليعلم أن قد أبلغوا رسالات ربهم وأحاط بما لديهم وأحصى كل شيء (72:28) بالانجليزي

(72:28) so that He may know that they have delivered the messages of their Lord. *29 He encompasses in His knowledge their surroundings and keeps a count of all things.' *30

Tafseer Abu-al-A'la Maududi

Page 573 English Traditional

*29) This can have three meanings: (1) That the Messenger may know that the angels have delivered the messages of AIIah to him precisely and accurately; (2) that Allah may know that the angels have conveyed the messages of their Lord to His Messenger precisely and accurately; and (3) that AIIah may know that the Messenger has conveyed the messages of his Lord to His servants precisely and accurately. The words of the verse are comprehensive and may possibly imply all the three meanings. Besides, the verse also points out two other things: first, that the Messenger is given that knowledge of the unseen, which is necessary for him to perform his mission of Prophethood; second, that the angels keep watch that the Revelation reaches the Messenger safely and also that the Messenger conveys the messages of his Lord to His servants precisely and accurately.
*30) That is, Allah's power so encompasses the Messenger as well as the angels that if they swerve even a little from His will, they can be detected immediately. Moreover, a complete record has been kept of each letter of the messages sent down by Allah. The Messengers and the angels cannot dare add or subtract even a letter from them.