Performing the Dhuhaa prayer at work
Question: Is it permissible for me to perform the Dhuhaa prayer during official work hours, keeping in mind that (doing so) does not cause any hindrance or delay in the work?
Response: The Dhuhaa prayer is a Sunnah, and there is excellence in it, and if you are at work and performing it does not affect the work which you have been charged with, then there is no harm in you performing it. However, if performing it affects your work, then it is not permissible for you to perform it since it interferes with you carrying out your (work) duties (which are) obligatory (upon you since you are being paid to do so).
Shaykh Saalih ibn Fowzaan
al-Muntaqaa min Fataawa Shaykh Saalih al-Fowzaan – Volume 5, Page 40, Fatwa No.59 fatwaonline.com