Someone asked Imam Sadiq (AS): o son of the Messenger of Allah! The Shiite companions tell a story that is hard to believe, Imam Sadiq (AS) said: tell me the story.
The person said:
Our Shiite companions say: someone passed away in Medina, his corpse was taken to the mosque, at that time everybody loved the holy prophet to perform the prayers for the dead body.
The family of the dead person pleaded the holy prophet to perform the prayers for him.
The Noble Prophet of Islam (pbuh) explicitly said: I do not perform the prayers for this person because he is owed two dinars, perform the prayers yourself.
The sin of not paying the debt is so much heavy and worse that the Messenger of Allah (PBUH) said: I do not perform the prayers for this person
source : erfan.ir