You asked what to say to her.

If you say nothing about the situation to your daughter then she will assume that what he tells her is true.

I think you should discuss it with her.

To me, the discussion would be factual, not judgmental of him.

The fact is that you did not forbid it.

In my mind you would tell her that you don’t know why her father said that, perhaps there was a misunderstanding, but it isn’t true.

I get that you don’t want to speak ill of him to her, that is admirable of you. But I don’t think you are required to throw yourself under the bus in her eyes to protect her image of him. Her image of you matters too. A lot.