You can argue until the cows come home, but I will not change my mind.
until the cows freeze over
idiomFor a very long period of time.
Origin
disputed originMixed metaphor combining until the cows come home + when hell freezes over.
We sat in the cafe talking about our future plans until the cows came home.
The committee debated the complex policy changes until the cows came home, yet they still failed to reach a final consensus.