Place it at the end of a request scene, after the question is asked, and follow it with Nope for a firmer second refusal or open with Okay Let's Go to set up a false yes before the turn. Keep it as the final beat so the edit ends on the rejection.
Sobre este som
This is a very short spoken line, lasting about a second, in which a calm voice delivers the words 'I'm afraid not' as a firm but courteous refusal. It feels dry, slightly awkward and quietly final, like a polite door closing on a request. The clipped delivery makes the no land harder than a longer explanation would.