How should one address a non-believer, especially if he is an employer? Is it permissible to use titles like "Mr." or "Monsieur" to address him, especially for a Muslim residing in non-Muslim lands, taking into consideration the noble Hadith: "Do not say 'Sayyiduna' (our master) to a hypocrite, for if he be your master, you have angered your Lord"?

The word "Sayyid" (master/lord) is used for an owner or the leader of a people. Scholars have differed on its application to an individual. Some have prohibited it based on the Prophet's (peace be upon him) saying: "The Sayyid is Allah." Others have permitted it based on his saying to the Ansar: "Stand up for your Sayyid," referring to Sa'd ibn Mu'adh.

As for applying the word "Sayyid" to a disbeliever (kafir), it is forbidden by Islamic law due to the Prophet's (peace be upon him) prohibition against saying "Sayyid" to a hypocrite, as it is an exaltation of someone undeserving. Indeed, some scholars even deem it forbidden to apply it to evildoers and innovators.

Therefore, it is not permissible to say "O Sayyid" to a disbeliever unless refraining from it would lead to a greater harm. One can address him by his name or teknonym. The Prophet (peace be upon him) addressed the Bishop of Najran as "O Abu al-Harith," and Umar (may Allah be pleased with him) addressed a Christian as "O Abu Hassan."