stubborn as a mule

"Michael knew all of this, but as his friends and family will attest, he was passionate, and stubborn as a mule."

“But age comes for us all, and Mitch is stubborn as a mule, and he’s tough. And so he’s been in my prayers in recent weeks.”

“And he’s stubborn as a mule, and I have every hope he recovers to full strength.”

“Mitch is strong, he’s stubborn as a mule,” Cruz said.

Like many Americans long removed from pastoral life, I still use its idioms, from “Hold your horses” and “stubborn as a mule” to “till the cows come home.”