Sayyiduna Ibn Abasah (may Allah be pleased with him) narrates: I saw the Prophet (peace and blessings be upon him) rinsing his mouth and sniffing water into his nose during Ramadan (while fasting).
Ahmad recorded it. Kathir bin Ziyad did not meet the time of Sayyiduna Ibn Abasah (may Allah be pleased with him).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصيام / 4956