How to persuade an employer/ manager that the proofreading is a substantial part before releasing a document?

Hi Eyad

From my point of view the key word is transparency, i recommend that you approach your manager be totally honest and transparent and advise him of the importance of proofreading, he may not be aware as it may be out of his interest or scope, approach him with the key important points. 

number one priority is the benefit of the company, you are not concerned for your own interest you are concerned for the interest of the company.

if the manager is good he should be happy with your concern and praise you!

Good luck!

Regards

Belal Hihi