What is the ruling on saying: "I will take my right from you on the Day of Resurrection before the Messenger of Allah, may Allah bless him and grant him peace," and "Will you not be ashamed on the Day of Resurrection before the Messenger of Allah, may Allah bless him and grant him peace?"?

What happens on the Day of Judgment is among the unseen matters, concerning which nothing can be asserted definitively except through revelation. It has not been established in revelation that those who have rights will litigate or be held accountable in the presence of the Prophet, peace and blessings be upon him.

If what the man promised was a debt upon him, then he must repay it; otherwise, it will be taken from his good deeds on the Day of Judgment. However, if it was a mere promise, then what is relied upon is that it is recommended, though some scholars have deemed it obligatory.