Sayyiduna Abu Ayyub (may Allah be pleased with him) narrates: When the Prophet (peace and blessings be upon him) performed ablution, he (peace and blessings be upon him) would rinse his mouth and wipe his beard with water from underneath.
Ahmad recorded it; its chain contains a narrator, Wasil bin al-Sa'ib, whose weakness the hadith scholars agree upon.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطهارة / 1168