Sahih Al Bukhari – Book of Transferance Of A Debt From One Person To Another (Al-Hawaala)

Volumn 003, Book 037, Hadith Number 492.
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Narated By Salama bin Al-Akwa RA: A dead person was brought to the Prophet PBUH so that he might lead the funeral prayer for him. He asked, "Is he in debt?" When the people PBUH replied in the negative, he led the funeral prayer. Another dead person was brought and he asked, "Is he in debt?" They said, "Yes." He PBUH (refused to lead the prayer and) said, "Lead the prayer of your friend." Abu Qatada RA said, "O Allah's Apostle! I undertake to pay his debt." Allah's Apostle then led his funeral prayer.