Is every command or prohibition of the Prophet, may Allah’s prayers and peace be upon him, considered an obligation or a prohibition, such as the command to grow a beard, and the command not to sit down upon entering the mosque until after performing the two rak'ahs of greeting the mosque?

The default rule concerning the command of the Prophet, peace and blessings be upon him, is that it denotes obligation, according to the majority of scholars. This is supported by the Almighty's saying: "And let those who oppose his command beware, lest fitnah strike them or there come upon them a painful punishment," and His saying: "And whatever the Messenger has given you - take; and what he has forbidden you - refrain from." However, there may be a dispelling factor from the Quran and Sunnah that shifts a command from obligation to recommendation or permissibility, and shifts a prohibition from حرمة (prohibition) to كراهة (dislike). The issue of تحية المسجد (greeting the mosque prayer) is a point of scholarly disagreement; some consider it obligatory, while others deem it recommended due to the existence of dispelling factors.