Sahih Bukhari Volume 006, Book 060, Hadith Number 194.
Narrated By Ibn Umar : When Abdullah bin Ubai died, his son 'Abdullah bin 'Abdullah came to Allah's Apostle who gave his shirt to him and ordered him to shroud his father in it. Then he stood up to offer the funeral prayer for the deceased, but 'Umar bin Al-Khattab took hold of his garment and said, "Do you offer the funeral prayer for him though he was a hypocrite and Allah has forbidden you to ask forgiveness for hypocrites?" The Prophet said, "Allah has given me the choice (or Allah has informed me) saying:
"Whether you, O Muhammad, ask forgiveness for them, or do not ask forgiveness for them, even if you ask forgiveness for them seventy times, Allah will not forgive them," (9.80) The he added, "I will (appeal to Allah for his sake) more than seventy times." So Allah's Apostle offered the funeral prayer for him and we too, offered the prayer along with him. Then Allah revealed: "And never, O Muhammad, pray (funeral prayer) for anyone of them that dies, nor stand at his grave. Certainly they disbelieved in Allah and His Apostle and died in a state of rebellion." (9.84)