From the letter written to Governors when Uthman (ra) became Caliph

“Know that justice consists of observing the needs of Muslims, enforcing their rights, and collecting taxes, and also respecting the rights of the Dhimmi [non-Muslim subjects living in an Islamic country, freely observing their own religious beliefs] and collecting their taxes that they agreed to pay, known as the Jizra]. Remain faithful to agreements, [even] with your enemies.”