Sayyiduna Amr bin Hurayth (may Allah be pleased with him) states: The Prophet (peace and blessings be upon him) would sometimes touch his beard in the prayer.
Abu Ya'la recorded it; its chain contains Muhammad bin al-Khattab, who is da'if (weak), and Imam Ibn Hibban (may Allah have mercy on him) mentioned him in the book al-Thiqat.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2465