Hadith 4:618
9484. 'Abd al-A'la narrated to us, from Hisham, from al-Hasan, that he used to say: If he rinses his mouth while he is fasting, and something enters his throat without him intending it, then there is nothing upon him; he should complete his fast.
حدثنا عبد الأعلى عن هشام عن الحسن أنه كان يقول إذا مضمض وهو صائم فدخل حلقه شيء لم يتعمده فليس عليه شيء يتم صومه