What is Shafa’ah (Intercession)?
It is the supplication and praying of the Prophet and some other great personalities to Allah for the forgiveness of some sinful believers and for the elevation of obedient believers to higher ranks on the Day of Judgment.
Our Prophet owns a great intercession that was not given to any other prophets. He will use that intercession on the Day of Judgment in order to enable people to be saved from the horror of Mahshar by finishing their reckoning.
His intercession on the Day of Judgment is called “Shafa’ah al-Uzma” (Great Intercession). That privilege and high rank of intercession given to our Prophet is called “Maqam al-Mahmud” (the Station of Praise and Glory).
Apart from the great intercession of our Prophet related to humanity, there will be his special intercession for his ummah.
"From Ibn Abbas: Hazrat Prophet reported the following from Ruhu'l-Amin (Hazrat Jibril): The rewards and sins of a person are brought on the Day of Judgment and calculated). Even if there is only one good deed left, Allah grants that person His bounties in Paradise." (Ibn Kathir)