Ishaq bin Isa al-Tabba' (may Allah have mercy on him) said: I saw Malik bin Anas (may Allah have mercy on him) with a full moustache, so I asked him about that. He narrated (with his chain) from Amir bin Abdullah bin al-Zubayr (may Allah have mercy on him) that whenever Umar bin al-Khattab (may Allah be pleased with him) became angry, he would twist his moustache and blow.
Hadith Referenceالمعجم الكبير للطبراني / العشرة / 53