Was the body of Prophet Muhammad SAW decomposing?

According to one Hadith : >The Prophet (peace be upon him) said: “Verily, Allah has forbidden the Earth to consume the bodies of the Prophets.” (Sunan Abî Dâwûd (1047), Sunan al-Nasâ’î (1374), and Sunan Ibn Mâjah (1636).) I found a contradictory report here http://www.ahl-alquran.com/arabic/printpage.php?doc_type=1&doc_id=15300 : >Al-Abbas, the paternal uncle of Prophet Muhammad, entered Muhammad's room three after his death, before his burial, as his body remained there for three days as the people were too busy to bury him, as all of them were engaged in debates of Al-Thaqeefa Council of choosing a ruler/caliph of Yathreb to succeed him. Once Al-Abbas entered the room, he put his hands at once at his nose, and said to the gathered men outside: "Bury your friend Muhammad fast, for HIS BODY BEGAN DECOMPOSITION just like the rest of human beings" … (capital emphasis mine) Where can this opposing Hadith be found. The link doesn't provide a source. Certain anti-islamists have used this to point out the "falsehood" (Nauzubillah) of Prophet Muhammad SAW bcuz he said the bodies do not decompose. I need help. Where can it be found and is it authentic?