كتاب البر والصلة والآداب
45
The Book of Virtue, Enjoining Good Manners, and Joining of the Ties of Kinship
(27)
Chapter: The Prohibition Of Lying, And What Is Permitted Thereof
(27)
باب تَحْرِيمِ الْكَذِبِ وَبَيَانِ مَا يُبَاحُ مِنْهُ ‏‏

Humaid b. 'Abd al-Rahman b. 'Auf reported that his mother Umm Kulthum daughter of 'Uqba b. Abu Mu'ait, and she was one amongst the first emigrants who pledged allegiance to Allah's Apostle (ﷺ), as saying that she heard Allah's Messenger (ﷺ) as saying:

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).
حَدَّثَنِي حَرْمَلَةُ بْنُ يَحْيَى، أَخْبَرَنَا ابْنُ وَهْبٍ، أَخْبَرَنِي يُونُسُ، عَنِ ابْنِ شِهَابٍ، أَخْبَرَنِي حُمَيْدُ بْنُ عَبْدِ الرَّحْمَنِ بْنِ عَوْفٍ، أَنَّ أُمَّهُ أُمَّ كُلْثُومٍ بِنْتَ عُقْبَةَ بْنِ أَبِي مُعَيْطٍ، وَكَانَتْ، مِنَ الْمُهَاجِرَاتِ الأُوَلِ اللاَّتِي بَايَعْنَ النَّبِيَّ صلى الله عليه وسلم أَخْبَرَتْهُ أَنَّهَا سَمِعَتْ رَسُولَ اللَّهِ صلى الله عليه وسلم وَهُوَ يَقُولُ ‏ "‏ لَيْسَ الْكَذَّابُ الَّذِي يُصْلِحُ بَيْنَ النَّاسِ وَيَقُولُ خَيْرًا وَيَنْمِي خَيْرًا ‏"‏ ‏.‏ قَالَ ابْنُ شِهَابٍ وَلَمْ أَسْمَعْ يُرَخَّصُ فِي شَىْءٍ مِمَّا يَقُولُ النَّاسُ كَذِبٌ إِلاَّ فِي ثَلاَثٍ الْحَرْبُ وَالإِصْلاَحُ بَيْنَ النَّاسِ وَحَدِيثُ الرَّجُلِ امْرَأَتَهُ وَحَدِيثُ الْمَرْأَةِ زَوْجَهَا ‏.‏
Reference : Sahih Muslim 2605 a
In-book reference : Book 45, Hadith 130
USC-MSA web (English) reference : Book 32, Hadith 6303
  (deprecated numbering scheme)