have a heart 有心；发发善心；有同情心

【例句】
Have a heart! I can't possibly get through that amount of work in such a short time.
发发善心吧！在这么短的时间里，我可不能完成那么多工作。

Please have a heart and let me off this time!
您行行好，就饶了我这一回吧！