The person asking for your time should make room for an honest answer.

An invitation delivered in a way that makes refusal awkward is not really a question. Asking in front of other people, asking with the plan already made, asking with a tone that assumes yes: each of these gets you an answer that means very little. The person says yes and then resents it, or cancels late, and the requester never understands why.

When you ask for someone’s time, say plainly that no is a fine answer and then be quiet. Ask privately rather than in a group. If you get a hesitation, treat it as a no rather than a starting position.