Sunan At-Tirmidhi

Ziyad bin Kusaib Al-'Adawi said:""I was with Abu Bakrah under the Minbar of Ibn 'Amir while he was giving a Khutbah wearing a fine garment. Abu Bilal said: 'Look at our Amir wearing clothes of wickedness!' So Abu Bakrah said: Be quiet! I heard the Messenger of Allah(s.a.w) saying: ""Whoever insults Allah's Sultan on the earth, Allah disgraces him