"I was sitting with the Prophet when some drink was brought, so he drank from it, then he offered it to me and I drank it. Then I said: 'I have indeed sinned, so seek forgiveness for me.' He said: 'What is that?' I said: 'I was fasting, then I broke the fast.' He said: 'Were you performing a fast that you had to make up?' I said: 'No.' He said: 'Then it is no harm for you.'"
حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا أَبُو الأَحْوَصِ، عَنْ سِمَاكِ بْنِ حَرْبٍ، عَنِ ابْنِ أُمِّ هَانِئٍ، عَنْ أُمِّ هَانِئٍ، قَالَتْ كُنْتُ قَاعِدَةً عِنْدَ النَّبِيِّ صلى الله عليه وسلم فَأُتِيَ بِشَرَابٍ فَشَرِبَ مِنْهُ ثُمَّ نَاوَلَنِي فَشَرِبْتُ مِنْهُ فَقُلْتُ إِنِّي أَذْنَبْتُ فَاسْتَغْفِرْ لِي . فَقَالَ " وَمَا ذَاكِ " . قَالَتْ كُنْتُ صَائِمَةً فَأَفْطَرْتُ . فَقَالَ " أَمِنْ قَضَاءٍ كُنْتِ تَقْضِينَهُ " . قَالَتْ لاَ . قَالَ " فَلاَ يَضُرُّكِ " . قَالَ وَفِي الْبَابِ عَنْ أَبِي سَعِيدٍ وَعَائِشَةَ .
Tirmizi
The Book on Fasting • Hadith 730