Short answer
No. An interest-free loan (qard hasan) is allowed, and lending to someone in need is rewarded. A loan becomes haram when the lender sets any extra as a condition, even between family or friends. Paying back a little more as a free gift, with nothing agreed or expected, is a sunnah.
Borrowing and lending without interest are permitted, and lending to someone in need is mustahabb. Any benefit the lender stipulates is riba and haram, including in loans between relatives. An unconditional extra at repayment is permitted and praiseworthy.
The four schools agree on this.
Explanation
Lending is a kindness in Islam. The Quran commands that debts be written down (2:282), asks lenders to give a struggling debtor time (2:280), and the Prophet ﷺ told of a trader who used to let off debtors in hardship, and Allah forgave him. See the ayah on writing debts.
Interest from family is still interest. If a relative says, "I will lend you $10,000 if you pay back $11,000," or "if you let me use your car for free until then," the loan has a stipulated benefit, and that is riba. Hanafi jurists apply the rule that every loan bringing the lender a stipulated benefit is riba. You must also repay the same amount you borrowed; a cash loan cannot be adjusted for inflation. A lender worried about inflation can lend in gold, to be repaid as the same weight of gold.
A gift on repayment is different. When the Prophet ﷺ repaid a camel with a better one, he said the best people are those who repay best. The extra must be your free choice at the time of repaying, not a term of the loan or an expected custom.
Borrow only what you need and with a firm intention to repay: whoever takes people's money intending to repay it, Allah will help him repay. The Prophet ﷺ often sought refuge from debt; see the dua for debt. The four schools agree on these rules.
The evidence
Quran, Surah Al-Baqara 2:282
يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوٓا۟ إِذَا تَدَايَنتُم بِدَيْنٍ إِلَىٰٓ أَجَلٍۢ مُّسَمًّۭى فَٱكْتُبُوهُ ۚ وَلْيَكْتُب بَّيْنَكُمْ كَاتِبٌۢ بِٱلْعَدْلِ ۚ وَلَا يَأْبَ كَاتِبٌ أَن يَكْتُبَ كَمَا عَلَّمَهُ ٱللَّهُ ۚ فَلْيَكْتُبْ وَلْيُمْلِلِ ٱلَّذِى عَلَيْهِ ٱلْحَقُّ وَلْيَتَّقِ ٱللَّهَ رَبَّهُۥ وَلَا يَبْخَسْ مِنْهُ شَيْـًۭٔا ۚ فَإِن كَانَ ٱلَّذِى عَلَيْهِ ٱلْحَقُّ سَفِيهًا أَوْ ضَعِيفًا أَوْ لَا يَسْتَطِيعُ أَن يُمِلَّ هُوَ فَلْيُمْلِلْ وَلِيُّهُۥ بِٱلْعَدْلِ ۚ وَٱسْتَشْهِدُوا۟ شَهِيدَيْنِ مِن رِّجَالِكُمْ ۖ فَإِن لَّمْ يَكُونَا رَجُلَيْنِ فَرَجُلٌۭ وَٱمْرَأَتَانِ مِمَّن تَرْضَوْنَ مِنَ ٱلشُّهَدَآءِ أَن تَضِلَّ إِحْدَىٰهُمَا فَتُذَكِّرَ إِحْدَىٰهُمَا ٱلْأُخْرَىٰ ۚ وَلَا يَأْبَ ٱلشُّهَدَآءُ إِذَا مَا دُعُوا۟ ۚ وَلَا تَسْـَٔمُوٓا۟ أَن تَكْتُبُوهُ صَغِيرًا أَوْ كَبِيرًا إِلَىٰٓ أَجَلِهِۦ ۚ ذَٰلِكُمْ أَقْسَطُ عِندَ ٱللَّهِ وَأَقْوَمُ لِلشَّهَٰدَةِ وَأَدْنَىٰٓ أَلَّا تَرْتَابُوٓا۟ ۖ إِلَّآ أَن تَكُونَ تِجَٰرَةً حَاضِرَةًۭ تُدِيرُونَهَا بَيْنَكُمْ فَلَيْسَ عَلَيْكُمْ جُنَاحٌ أَلَّا تَكْتُبُوهَا ۗ وَأَشْهِدُوٓا۟ إِذَا تَبَايَعْتُمْ ۚ وَلَا يُضَآرَّ كَاتِبٌۭ وَلَا شَهِيدٌۭ ۚ وَإِن تَفْعَلُوا۟ فَإِنَّهُۥ فُسُوقٌۢ بِكُمْ ۗ وَٱتَّقُوا۟ ٱللَّهَ ۖ وَيُعَلِّمُكُمُ ٱللَّهُ ۗ وَٱللَّهُ بِكُلِّ شَىْءٍ عَلِيمٌۭ ﴿٢٨٢﴾
O you who have believed, when you contract a debt for a specified term, write it down. And let a scribe write [it] between you in justice. Let no scribe refuse to write as Allah has taught him. So let him write and let the one who has the obligation dictate. And let him fear Allah, his Lord, and not leave anything out of it. But if the one who has the obligation is of limited understanding or weak or unable to dictate himself, then let his guardian dictate in justice. And bring to witness two witnesses from among your men. And if there are not two men [available], then a man and two women from those whom you accept as witnesses - so that if one of the women errs, then the other can remind her. And let not the witnesses refuse when they are called upon. And do not be [too] weary to write it, whether it is small or large, for its [specified] term. That is more just in the sight of Allah and stronger as evidence and more likely to prevent doubt between you, except when it is an immediate transaction which you conduct among yourselves. For [then] there is no blame upon you if you do not write it. And take witnesses when you conclude a contract. Let no scribe be harmed or any witness. For if you do so, indeed, it is [grave] disobedience in you. And fear Allah. And Allah teaches you. And Allah is Knowing of all things.
Loans are lawful and should be recorded.
Quran, Surah Al-Baqara 2:280
وَإِن كَانَ ذُو عُسْرَةٍۢ فَنَظِرَةٌ إِلَىٰ مَيْسَرَةٍۢ ۚ وَأَن تَصَدَّقُوا۟ خَيْرٌۭ لَّكُمْ ۖ إِن كُنتُمْ تَعْلَمُونَ ﴿٢٨٠﴾
And if someone is in hardship, then [let there be] postponement until [a time of] ease. But if you give [from your right as] charity, then it is better for you, if you only knew.
Lenders are asked to give a struggling debtor time.
Sahih al-Bukhari 2305
Sahih... إن خياركم أحسنكم قضاء ...
"The best of you are those who are best in repaying."
Giving back more of your own accord, with no prior condition, is praiseworthy.
Sahih al-Bukhari 2387
Sahih... من أخذ أموال الناس يريد أداءها أدى الله عنه ...
"Whoever takes people's wealth intending to repay it, Allah will repay it for him."
Borrowing is allowed with a sincere intention to repay.
Where the ruling is recorded
- al-Durr al-Mukhtar, Kitab al-Buyu', Fasl fi al-Qard. Every loan that brings the lender a stipulated benefit is haram, and a loan is repaid with its like.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Buyu', Fasl fi al-Qard. An extra given at repayment without condition is permitted.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.