Mr. Gabriel has given valuable advice. Kindly follow it.
The appointment letter/certified standing orders/employee rule book should be studied carefully before taking up or agreeing to take up any assignment. At times employer may become unforgiving.
Some of the employer might have expressed in the rules that employee shall need to obtain permission in writing to take up even honorary job without honorarium.
In case the employee wants to write articles in newspaper/magazine without any reward in cash or kind/ honorarium, the employee should apply in writing with full details and obtain explicit consent in writing.
At the same time some companies may have certain activities e.g. CSR in their schedule and may encourage employees to participate and write on these.