Musannaf Ibn Abi Shayba 17:177

Ma'n ibn 'Isa narrated to us, from Muhammad ibn Hilal, who said: I saw Sa'id ibn al-Musayyib, 'Umar ibn 'Abd al-'Aziz, Salim, 'Urwah ibn al-Zubayr, Ja'far ibn al-Zubayr, 'Ubayd Allah ibn 'Abd Allah ibn 'Utbah, and Abu Bakr ibn 'Abd al-Rahman ibn al-Harith ibn Hisham. They did not trim their mustaches excessively; they would take from them in a good manner.