stick to one's guns

stick to one's guns or stand by one's guns  {v. phr.}

To hold to an aim or an opinion even though people try to stop you or say you are wrong.

People laughed at Columbus when he said the world was round. He stuck to his guns and proved he was right.

At first the boss would not give Jane the raise in pay she wanted, but she stood by her guns and he gave it to her.

Compare: STAND ONE'S GROUND.