And ‘Umar (or Ibn ‘Umar), may Allah be pleased with them both, used to trim the mustache so much that the whiteness of the skin would become visible, and the hair between the mustache and the beard (on the chin), meaning the hair in the middle, he would have them cut off.

Narrated Ibn `Umar: The Prophet said, "To get the moustaches cut 'short is characteristic of the Fitra."

Narrated Abu Huraira: Allah's Apostle said, "Five practices are characteristics of the Fitra: circumcision, shaving the pubic region, clipping the nails and cutting the moustaches short."