Take a rain check
American SlangDefinition
Politely decline an invitation or offer for now, suggesting you’ll do it at a later time; to postpone.
Examples
"I’d love to join you for dinner, but can I take a rain check and do it later this week?"
"Thanks for the invite to the game; I’ll have to take a rain check—let’s plan for the next one."
"I’m in the middle of a project right now, so I’ll take a rain check on coffee and meet up tomorrow."