Trust any Muslim to tell the Truth you must be Joking
The primary Quranic verse sanctioning deception with respect to non-Muslims states: "Let believers not take for friends and allies infidels instead of believers. Whoever does this shall have no relationship left with Allah – unless you but guard yourselves against them, taking precautions." (Quran 3:28; see also 2:173; 2:185; 4:29; 22:78; 40:28.)
Al-Tabari's (838-923 AD) Tafsir, or Quranic exegeses, is essentially a standard reference in the entire Muslim world. Regarding 3:28, he wrote: "If you [Muslims] are under their [infidels'] authority, fearing for yourselves, behave loyally to them, with your tongue, while harbouring inner animosity for them... Allah has forbidden believers from being friendly or on intimate terms with the infidels in place of believers – except when infidels are above them [in authority]. In such a scenario, let them act friendly towards them."
Regarding 3:28, the Islamic scholar Ibn Kathir (1301-1373) wrote: "Whoever at any time or place fears their [infidels'] evil, may protect himself through outward show."
As proof of this, he quotes Muhammad's companions. Abu Darda said: "Let us smile to the face of some people while our hearts curse them." Al-Hassan said: "Doing taqiyya is acceptable till the day of judgment [in perpetuity]."
Other prominent ulema, such as al- Qurtubi , al-Razi, and al-Arabi have extended taqiyya to cover deeds. Muslims can behave like infidels – from bowing down and worshipping idols and crosses to even exposing fellow Muslims' "weak spots" to the infidel enemy – anything short of actually killing a fellow Muslim.
War is deceit
None of this should be surprising considering that Muhammad himself, whose example as the "most perfect human" is to be tenaciously followed, took an expedient view on the issue of deception. For instance, Muhammad permitted deceit in three situations: to reconcile two or more quarreling parties; husband to wife and vice-versa; and in war (See Sahih Muslim B32N6303, deemed an "authentic" hadith).
During the Battle of the Trench (627 AD), which pitted Muhammad and his followers against several non-Muslim tribes collectively known as "the Confederates", a Confederate called Naim bin Masud went to the Muslim camp and converted to Islam. When Muhammad discovered the Confederates were unaware of Masud's conversion, he counseled him to return and try somehow to get his tribesmen to abandon the siege. "For war is deceit," Muhammad assured him.
Masud returned to the Confederates without their knowledge that he had switched sides and began giving his former kin and allies bad advice. He also went to great lengths to instigate quarrels between the various tribes until, thoroughly distrusting each other, they disbanded and lifted the siege. According to this account, deceit saved Islam during its embryonic stage (see Al-Taqiyya Fi Al-Islam; also, Ibn Ishaq's Sira, the earliest biography of Muhammad).
More demonstrative of the legitimacy of deception with respect to non-Muslims is the following account. A poet, Kab bin al-Ashruf, had offended Muhammad by making derogatory verse about Muslim women. Muhammad exclaimed in front of his followers: "Who will kill this man who has hurt Allah and his prophet?"
A young Muslim named Muhammad bin Maslama volunteered, but with the caveat that, in order to get close enough to Kab to assassinate him, he be allowed to lie to the poet. Muhammad agreed.