Does it need validation data for fit()?

[DynastyTHU]

I found that in every example which used fit(), there was always setValidate() before. However I wanted to process the data for test afterwards and I didn't want to separate an extra part for validation. I also found that the cross validation cv() didn't need extra validation data but it didn't contain a path to save the model so how could I use the model for prediction afterwards?