Wonder Of Quranic Arabic - The invocation of Moses to Allah and The Response Surah QAsas

           

when Moses prays to God to make Aaron his assistant:

  (20:31)   وَاَشۡرِكۡهُ فِىۡۤ اَمۡرِىْ ۙ‏

“Strengthen my back with him.”

28:35, in reply to this prayer, Allah says,
 

قَالَ سَنَشُدُّ عَضُدَكَ بِاَخِيۡكَ

“We shall strengthen your arm with him.” 

“To strengthen one’s back” is like providing “backing”, while “to strengthen one’s

arm” is like providing “muscle”. As such, the former suggests furnishing A support

through B in a situation where the brunt of the task will be borne by A but B, who is

standing close by―“in back of him”―may be called upon to help when necessary.

“To strengthen one’s arm” on the other hand, would suggest providing A with support

through B in a situation where B will be an active partner to A throughout, or will be

A’s “right arm.”