excuse ***
beg off

My friends tried to help me, but I begged them off.

However he had to beg off due to health reasons.

They'd asked her if she didn't want to come with them, but she'd begged off.

The captain begged off and sat down, saying he was exhausted.

But then he added, 'It's not going to be easy to beg off.

At first she begged off going to my place, wanted to do it in the back seat of the car.

If he tried to beg off, that would be bad.

That's why he tried to beg off, but he's afraid of me.

"I asked him to stay to dinner, but he begged off."

She had, indeed, tried to beg off going to London herself.