✅ Lying, as a major sin, has been severely condemned in verses and narrations. In this brief text, some cases of the permissibility of lying and falsehood are explained in the narrations:

1 فِي وَصِيَّةِ النَّبِيِّ لِعَلِيٍّ قَالَ: يَا عَلِيُّ إِنَّ اللَّهَ أَحَبَّ الْكَذِبَ فِي الصَّلَاحِ وَ أَبْغَضَ الصِّدْقَ فِي الْفَسَادِ إِلَى أَنْ قَالَ يَا عَلِيُّ ثَلَاثٌ يَحْسُنُ فِيهِنَّ الْكَذِبُ الْمَكِيدَةُ فِي الْحَرْبِ وَ عِدَتُكَ زَوْجَتَكَ وَ الْإِصْلَاحُ بَيْنَ النَّاس

📚 Al-Faqih, Vol. 4, p. 359

The Messenger of Allah (peace be upon him and his family) said in his will to Amir al-Mu'minin (peace be upon him): 'O Ali, indeed Allah loves lying for reform and hates truthfulness for corruption.' Until he said: 'There are three places where lying is good: for cunning and scheming in war, for promising your wife, and for making peace between people.'

2 Imam Sadiq (peace be upon him) said: 'A peacemaker is not a liar.'

📚 Al-Kafi, Vol. 2, p. 342

3 Hasan al-Sayqal said: 'I said to Imam Sadiq (peace be upon him): 'We have narrated from Imam Baqir (peace be upon him) concerning the saying of Yusuf (peace be upon him) who said: 'O caravan, you are thieves,' that he said: 'By Allah, they did not steal, and Yusuf did not lie.' And concerning Ibrahim (peace be upon him) who said: 'Rather, this greatest of them did it, so ask them if they can speak,' he said: 'By Allah, they did not do it, and Ibrahim did not lie.' The Imam said: 'What do you have about this?' I said: 'We have nothing but submission.' He said: 'Indeed, Allah loves two things and hates two things: He loves walking with pride between two ranks (of truth and falsehood in jihad) and lying for reform, and He hates walking with pride on the roads and truthfulness that is not for reform. Indeed, Ibrahim (peace be upon him) said, with the intention of reform and to indicate that those idols do not do anything: 'Rather, their greatest one did this,' and Yusuf also said that with the intention of reform.'

📚 Al-Kafi, Vol. 2, p. 341

4 عِيسَى بْن حَسَّان قَالَ سَمِعْتُ أَبَا عَبْدِ اللَّهِ يَقُولُ كُلُّ كَذِبٍ مَسْئُولٌ عَنْهُ صَاحِبُهُ يَوْماً إِلَّا كَذِباً في ثَلَاثَةٍ رَجُلٍ كَائِدٍ فِي حَرْبِه فَهُوَ مَوْضُوعٌ عَنْهُ أَوْ رَجُلٍ أَصْلَحَ بَيْن اثْنَيْنِ يَلْقَى هَذَا بِغَيْرِ مَا يَلْقَى بِهِ هَذَا يُرِيد بِذَلِك الْإِصْلَاحَ مَا بَيْنَهُمَا أَوْ رَجُلٍ وَعَدَ أَهْلَهُ شَيْئاً وَ هُوَ لَا يُرِيدُ أَنْ يُتِمَّ لَهُمْ

📚 Al-Kafi, Vol. 2, p. 342

Isa said: 'I heard Imam Sadiq (peace be upon him) say: 'Every lie will be questioned about its owner one day except for three cases: a person who schemes in war, for it is lifted from him; or a person who makes peace between two people and meets this one in a way that is different from how he meets the other, and his intention is to make peace between them; and a man who promises his family but does not intend to fulfill it for them.'

5 عَنْ أَبِي عَبْدِ اللَّهِ قَالَ:الْكَلَامُ ثَلَاثَةٌ صِدْقٌ و كَذِبٌ و إِصْلَاحٌ بَيْنَ النَّاسِ قَالَ قِيلَ لَهُ جُعِلْتُ فِداك ما الْإِصْلَاح بَيْنَ الناس قال تَسْمَعُ مِن الرَّجُلِ كلَاماً يَبْلُغُهُ فَتَخْبُثُ نَفْسُهُ فَتَقُولُ سَمِعْتُ مِنْ فُلَانٍ قَالَ فِيكَ مِن الْخَيْرِ كَذَاوكَذَا خِلَافَ مَا سَمِعْتَ مِنْه

Imam Sadiq (peace be upon him) said: 'Speech is of three types: truth, falsehood, and making peace between people.' He said: 'It was said: 'What is making peace between people?' He said: 'You hear a word about a person that, if it reaches him, will make his inner being (towards that person) corrupt, so you meet him and say the opposite of what you heard: 'I heard so-and-so saying such and such good things about you.''

📚 Al-Kafi, Vol. 2, p. 341

6 عَن الرِّضَا قَالَ:إِنَّ الرَّجُلَ لَيَصْدُق عَلَى أَخِيه فَيَنَالُهُ عَنَتٌ مِنْ صِدْقِهِ فَيكُون كَذَّاباً عند اللَّه و إِنَّ الرَّجُلَ لَيَكْذِب على أَخِيه يُرِيد بِه نَفْعَهُ فَيَكُونُ عِنْدَ اللَّهِ صَادِقاً

📚 Musadaqat al-Ikhwan, p. 76

Imam Ridha (peace be upon him) said: 'Indeed, a person says a truthful word to his brother, and as a result, he suffers hardship from this truthfulness, and as a result, such a person is considered a liar with Allah. And indeed, a person tells a lie to his brother, and his intention is to benefit him, and as a result, he is considered a truthful person with Allah.'

7 The Messenger of Allah (peace be upon him and his family) said: 'Make a false oath by Allah and save your brother from death.'

📚 Al-Tahdhib, Vol. 8, p. 300

✅ Alongside the severe condemnation of lying in Shi'a narrations, there is no doubt about the permission and even encouragement regarding some of its cases, one of which is for making peace between people. However, the important point is that it is necessary to perform these permissible cases in their right place with proper understanding and not to use the excuse of expediency to place them in an improper place. And also, we should be careful that truthfulness is condemned in some places.