Is wudoo’ invalidated if a person rinses his mouth without putting his finger in his mouth, because the Prophet (peace and blessings of Allaah be upon him) used to rinse his mouth with his finger? Is this report about him (peace and blessings of Allaah be upon him) saheeh?
Wudoo’ is valid even if one does not insert one’s finger in one's mouth when rinsing it. The report mentioned was narrated by Imaam Ahmad with a da’eef (weak) isnaad.
Fataawa al-Lajnah al-Daa’imah, 5/208