Texts from the Quran and from Sahih al-Bukhari and Sahih Muslim about keeping promises. This is a collection of texts, not a ruling and not a fatwa. For your own situation, ask a qualified scholar. All topics
From the Quran
يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوٓا۟ أَوْفُوا۟ بِٱلْعُقُودِ ۚ أُحِلَّتْ لَكُم بَهِيمَةُ ٱلْأَنْعَٰمِ إِلَّا مَا يُتْلَىٰ عَلَيْكُمْ غَيْرَ مُحِلِّى ٱلصَّيْدِ وَأَنتُمْ حُرُمٌ ۗ إِنَّ ٱللَّهَ يَحْكُمُ مَا يُرِيدُ
O you who have believed, fulfill [all] contracts. Lawful for you are the animals of grazing livestock except for that which is recited to you [in this Qur'an] – hunting not being permitted while you are in the state of ihram. Indeed, Allah ordains what He intends.
وَأَوْفُوا۟ بِعَهْدِ ٱللَّهِ إِذَا عَٰهَدتُّمْ وَلَا تَنقُضُوا۟ ٱلْأَيْمَٰنَ بَعْدَ تَوْكِيدِهَا وَقَدْ جَعَلْتُمُ ٱللَّهَ عَلَيْكُمْ كَفِيلًا ۚ إِنَّ ٱللَّهَ يَعْلَمُ مَا تَفْعَلُونَ
And fulfill the covenant of Allah when you have taken it, [O believers], and do not break oaths after their confirmation while you have made Allah, over you, a witness. Indeed, Allah knows what you do.
وَٱلَّذِينَ هُمْ لِأَمَٰنَٰتِهِمْ وَعَهْدِهِمْ رَٰعُونَ
And they who are to their trusts and their promises attentive
۞ لَّيْسَ ٱلْبِرَّ أَن تُوَلُّوا۟ وُجُوهَكُمْ قِبَلَ ٱلْمَشْرِقِ وَٱلْمَغْرِبِ وَلَٰكِنَّ ٱلْبِرَّ مَنْ ءَامَنَ بِٱللَّهِ وَٱلْيَوْمِ ٱلْءَاخِرِ وَٱلْمَلَٰٓئِكَةِ وَٱلْكِتَٰبِ وَٱلنَّبِيِّۦنَ وَءَاتَى ٱلْمَالَ عَلَىٰ حُبِّهِۦ ذَوِى ٱلْقُرْبَىٰ وَٱلْيَتَٰمَىٰ وَٱلْمَسَٰكِينَ وَٱبْنَ ٱلسَّبِيلِ وَٱلسَّآئِلِينَ وَفِى ٱلرِّقَابِ وَأَقَامَ ٱلصَّلَوٰةَ وَءَاتَى ٱلزَّكَوٰةَ وَٱلْمُوفُونَ بِعَهْدِهِمْ إِذَا عَٰهَدُوا۟ ۖ وَٱلصَّٰبِرِينَ فِى ٱلْبَأْسَآءِ وَٱلضَّرَّآءِ وَحِينَ ٱلْبَأْسِ ۗ أُو۟لَٰٓئِكَ ٱلَّذِينَ صَدَقُوا۟ ۖ وَأُو۟لَٰٓئِكَ هُمُ ٱلْمُتَّقُونَ
Righteousness is not that you turn your faces toward the east or the west, but [true] righteousness is [in] one who believes in Allah, the Last Day, the angels, the Book, and the prophets and gives wealth, in spite of love for it, to relatives, orphans, the needy, the traveler, those who ask [for help], and for freeing slaves; [and who] establishes prayer and gives zakah; [those who] fulfill their promise when they promise; and [those who] are patient in poverty and hardship and during battle. Those are the ones who have been true, and it is those who are the righteous.
بَلَىٰ مَنْ أَوْفَىٰ بِعَهْدِهِۦ وَٱتَّقَىٰ فَإِنَّ ٱللَّهَ يُحِبُّ ٱلْمُتَّقِينَ
But yes, whoever fulfills his commitment and fears Allah – then indeed, Allah loves those who fear Him.
ٱلَّذِينَ يُوفُونَ بِعَهْدِ ٱللَّهِ وَلَا يَنقُضُونَ ٱلْمِيثَٰقَ
Those who fulfill the covenant of Allah and do not break the contract,
وَلَا تَشْتَرُوا۟ بِعَهْدِ ٱللَّهِ ثَمَنًۭا قَلِيلًا ۚ إِنَّمَا عِندَ ٱللَّهِ هُوَ خَيْرٌۭ لَّكُمْ إِن كُنتُمْ تَعْلَمُونَ
And do not exchange the covenant of Allah for a small price. Indeed, what is with Allah is best for you, if only you could know.
وَٱذْكُرْ فِى ٱلْكِتَٰبِ إِسْمَٰعِيلَ ۚ إِنَّهُۥ كَانَ صَادِقَ ٱلْوَعْدِ وَكَانَ رَسُولًۭا نَّبِيًّۭا
And mention in the Book, Ishmael. Indeed, he was true to his promise, and he was a messenger and a prophet.
From the hadith
آيَةُ الْمُنَافِقِ ثَلاَثٌ إِذَا حَدَّثَ كَذَبَ، وَإِذَا اؤْتُمِنَ خَانَ، وَإِذَا وَعَدَ أَخَلَفَ
Narrated Abu Huraira:Allah's Messenger (ﷺ) said, "The signs of a hypocrite are three: (1) whenever he speaks, he tells a lie, (2) whenever he is entrusted, he proves to be dishonest, (3) whenever he promises, he breaks his promise
أَرْبَعٌ مَنْ كُنَّ فِيهِ كَانَ مُنَافِقًا خَالِصًا، وَمَنْ كَانَتْ فِيهِ خَصْلَةٌ مِنْهُنَّ كَانَتْ فِيهِ خَصْلَةٌ مِنَ النِّفَاقِ حَتَّى يَدَعَهَا إِذَا اؤْتُمِنَ خَانَ وَإِذَا حَدَّثَ كَذَبَ وَإِذَا عَاهَدَ غَدَرَ، وَإِذَا خَاصَمَ فَجَرَ ". تَابَعَهُ شُعْبَةُ عَنِ الأَعْمَشِ.
Narrated 'Abdullah bin 'Amr: The Prophet (ﷺ) said, "Whoever has the following four (characteristics) will be a pure hypocrite and whoever has one of the following four characteristics will have one characteristic of hypocrisy unless and until he gives it up. 1. Whenever he is entrusted, he betrays. 2. Whenever he speaks, he tells a lie. 3. Whenever he makes a covenant, he proves treacherous. 4. Whenever he quarrels, he behaves in a very imprudent, evil and insulting manner
Quran verses use the Arabic text with the Sahih International translation. Hadith are from Sahih al-Bukhari and Sahih Muslim. A translation is not the Quran itself, and one text does not give a full ruling. Open each link and read the text in its full context.