Using the office phone and taking a rest at work without permission
What is the ruling with regards to taking out time at work whether that is little or a lot, and also the ruling with regards to using the work telephone (for personal use)?
You are entrusted with the work you do and Allaah (Glorified Be He and free is He from all imperfections) stated:
يَا أَيُّهَا الَّذِينَ آمَنُوا لَا تَخُونُوا اللَّهَ وَالرَّسُولَ وَتَخُونُوا أَمَانَاتِكُمْ وَأَنتُمْ تَعْلَمُونَ
O you who believe! Betray not Allah and His Messenger, nor betray knowingly your Amanat (things entrusted to you, and all the duties which Allah has ordained for you). [8:27]
It is betrayal to take from that which you are entrusted (without permission), even if your boss excuses you. That is because maybe he is not the one in charge of this (i.e. he is not the one with the authority to excuse you). But if he is the one in charge and gives you permission (to take time out), there is no harm in taking it.
As for the work telephone or other things, it is better to refrain from using them out fear of falling into some unlawful. However, if (using the office phone for personal use) is something known amongst everyone in the office (i.e. known to both employer and employees) and no one says anything about it (i.e. objects), there is no harm using it InshaaAllaah.
[Source: Fadaa’il al Amaal’ pages 7-8, by Shaikh Muhammad Bin Abdullaah As-Subayyil (rahimahullaah)]