I say, and with God's success: It is recommended to rinse the mouth three times with fresh water for each rinse. Narrated by Talha ibn Masrif from his father from his grandfather: "The Messenger of God (peace be upon him) performed ablution and rinsed his mouth three times, and sniffed water three times, taking fresh water for each one." In Al-Mu'jam Al-Kabir 19: 180, Al-Tahanawi said in I'laa Al-Sunan 1: 56: The owner of Al-Siyaayah authenticated the hadiths of Talha ibn Masrif from his father from his grandfather, and confirmed the imams' reliance on his hadith from his father, supported by the silence of Abu Dawood and then Al-Mundhiri about him, and the improvement by Ibn Al-Salah. Al-Ayni said: Abu Dawood was silent about him, which is evidence of his approval of its authenticity. The definition of rinsing is to encompass the entire mouth, with emphasis on reaching the back of the throat. See: Fath Bab Al-'Inayah 1: 37, Sharh Al-Wiqayah p. 80, and Umdah Al-Ri'ayah 1: 63, and God knows best.