A liar is not one who tries to bring reconciliation amongst people and speaks good (in order to avert dispute), or he conveys good. Ibn Shihab said he did not hear that exemption was granted in anything what the people speak as lie but in three cases: in battle, for bringing reconciliation amongst persons and the narration of the words of the husband to his wife, and the narration of the words of a wife to her husband (in a twisted form in order to bring reconciliation between them). (Using translation from Muslim 2605a)   

أَنَّهَا سَمِعَتْ رَسُولَ اللهِ ﷺ يَقُولُ لَيْسَ الْكَذَّابُ الَّذِي يُصْلِحُ بَيْنَ النَّاسِ فَيَقُولَ خَيْرًا أَوْ يُنَمِّيَ خَيْرًا وَلَمْ يُرَخِّصْ فِي شَيْءٍ مِمَّا يَقُولُ النَّاسُ إِنَّهُ كَذِبٌ إِلَّا فِي ثَلَاثٍ «فِي الْحَرْبِ وَالْإِصْلَاحِ بَيْنَ النَّاسِ وَحَدِيثِ الرَّجُلِ امْرَأَتَهُ وَحَدِيثِ الْمَرْأَةِ زَوْجَهَا»