be (as) stubborn as a mule

To be very devoted to a particular opinion or course of action, especially when faced with opposition. My toddler is as stubborn as a mule and has a tantrum every night at bedtime because he doesn't want to stop playing. You'll never get Rich to change his opinion—he's stubborn as a mule.

Common Names:

Name	Pronounced	Usage
LÉOnce	-	French
Firuzeh	-	Persian
FraÑSez	-	Breton
Trenton	TREN-tən	English
Constantinus	-	Late Roman
Brian	BRIE-ən (Irish, English)	Irish, English, Ancient Irish