Banu Tamim
The Banu Tamim were a tribe who fought alongside Muhammad and helped in the Battle of Hunayn and Conquest of Mecca. However, when Muhammad sent a delegation led by Uyainah bin Hisn to collect tax (or zakat, which he made obligatory), the Banu al-Anbar, a sub-tribe of the Banu Tamim, refused to pay it. Instead they attacked him and forced him out of the territory, even before he could ask for the tax.