قَالَ يَحْيَى : سَمِعْتُ مَالِكًا , يَقُولُ : مَنْ أَكَلَ أَوْ شَرِبَ سَاهِيًا أَوْ نَاسِيًا فِي صِيَامِ تَطَوُّعٍ ، فَلَيْسَ عَلَيْهِ قَضَاءٌ ، وَلْيُتِمَّ يَوْمَهُ الَّذِي أَكَلَ فِيهِ أَوْ شَرِبَ وَهُوَ مُتَطَوِّعٌ ، وَلَا يُفْطِرْهُ وَلَيْسَ عَلَى مَنْ أَصَابَهُ أَمْرٌ يَقْطَعُ صِيَامَهُ وَهُوَ مُتَطَوِّعٌ قَضَاءٌ ، إِذَا كَانَ إِنَّمَا أَفْطَرَ مِنْ عُذْرٍ غَيْرَ مُتَعَمِّدٍ لِلْفِطْرِ ، وَلَا أَرَى عَلَيْهِ قَضَاءَ صَلَاةِ نَافِلَةٍ إِذَا هُوَ قَطَعَهَا مِنْ حَدَثٍ لَا يَسْتَطِيعُ حَبْسَهُ مِمَّا يَحْتَاجُ فِيهِ إِلَى الْوُضُوءِ
Imam Malik, may Allah have mercy on him, said: If a person, while observing a voluntary fast, eats or drinks out of forgetfulness, then there is no making up (qada) required for him, and he should complete that fast, because his fast is not invalidated. And if, during a voluntary fast, something involuntary occurs that breaks the fast (for example, menstruation begins or illness occurs), then making up (qada) is not obligatory, when he has broken the fast due to an excuse and not intentionally. Similarly, if someone starts a voluntary prayer and then breaks it due to an involuntary event (such as losing ablution), then there is no making up (qada) required for him.