With the tongue you are able to deliver what is in your heart, therefore refrain yourselves from telling lies whether for real or playful. Lying in humor will soon make you lie in earnest. Imam Ghazali said lying is a major sin, and the Nabi (saw) once said (what we understand from it):
Fear telling lies, liars are companies of the sinners, and both will be in Hell.
Lying is a door from doors of nifaq (hypocrisy).
Know that telling lies sometimes becomes obligatory (wajib) and sometimes allowed (mubah) due to need.
If lying is the only way out, then it becomes obligatory in these cases:
1. To prevent a person from being killed by a tyrant
2. To prevent another person’s property from being seized by tyrant
3. To safeguard another muslim’s wife or property from a tyrant.
If there is no other way, lying is allowed in these circumstances:
1. To make peace between opposing or arguing parties
2. To make peace between conflicting wives