He was sure that Jaskier remembered what happened last time he gave an opinion on the singing. The whole djinn sort of solidified the no singing rule in Geralt's book. No need to cause a stir again.
So he changed the subject. A swift avoidance from the Witcher in hopes to delay or stop a possible argument.
"Wouldn't you rather tell me about your days before joining me? I'm sure something faired importance."