I could not but believe every word of what he had said.

But on the other hand, she seemed to want to believe every word he said.

But I do not believe a word of what they say.

And no one should ever believe a word he says.

I couldn't make out for the moment whether to believe a word of what he said.

I didn't believe a word of what he was saying.

They didn't believe a word we told them at first.

He did not believe a single word of her story.

How likely was he to believe a word she said then?

She did not seem to believe her own words, though.