Hadith 661
It is narrated from Sayyida Umm Kulthum bint Uqbah (may Allah be pleased with her): I never saw the Noble Prophet (peace and blessings be upon him) permitting any lie except in three matters. The Noble Prophet (peace and blessings be upon him) said: "I do not consider them to be lies: one is a person who brings reconciliation between people with it (i.e., with a lie), one is who speaks something during war, and the third is when a husband and wife talk to each other."