Hadith 9540
٩٥٤٠ - حدثنا أبو بكر بن عياش عن ليث عن مجاهد قال: إذا كان على الرجل قضاء من رمضان فتطوع فهو (قضاؤه) (١) وإن لم يرده.
Hazrat Mujahid says that if a person owes a missed fast of Ramadan and he keeps a voluntary (nafl) fast, then it will be counted as his missed (qada) fast, even if he did not intend it as such.