Is the Hadith: "I will continue to intercede with my Lord, and He will grant my intercession until I said: 'O my Lord, grant me intercession for whoever said: "There is no god but Allah,"' whereupon He said: 'O Muhammad, this is not for you, nor for anyone else. By My might, My majesty, and My mercy, I will not leave anyone in the Fire who said: "There is no god but Allah,"'" authentic?

This is an authentic hadith and one of the hadiths about intercession (shafa'ah). Anas ibn Malik narrated that on the Day of Resurrection, people will turn to the prophets (Adam, Ibrahim, Musa, Isa) to intercede for them. Each of them will excuse themselves and direct the people to the next, until they reach Muhammad, peace be upon him. He will say, "I am worthy of it." Then he will prostrate to his Lord and praise Him, and it will be said to him, "Raise your head, speak and you will be heard, ask and you will be given, intercede and your intercession will be accepted." So he will intercede for his Ummah three times, and those who have an atom's weight of faith in their hearts will be brought out of the Fire. On the fourth time, he will seek permission for those who said "La ilaha illallah (there is no god but Allah)," whereupon Allah will say, "That is not for you - or He said: That is not up to you - but by My Might, My Majesty, My Grandeur, and My Sovereignty, I will certainly bring out whoever said, 'La ilaha illallah.'"

Muslim narrated that the Prophet, peace be upon him, said: "Every prophet has a supplication that is answered, and every prophet hastened to make his supplication, but I have reserved my supplication as intercession for my Ummah on the Day of Resurrection. It will reach, Allah willing, whoever dies from my Ummah and did not associate anything with Allah."

Reconciling the two hadiths: Al-'Iraqi indicated that the intercession granted to the Prophet, peace be upon him, is for the monotheists of this Ummah, and what Allah reserved for Himself is for the monotheists of other nations. Stronger than that is what Ibn Hajar mentioned: that the meaning of "That is not for you" refers to the direct act of bringing out, not the principle of intercession itself. He explained that this final intercession occurred in bringing out those mentioned, and while the principle of bringing them out was accepted, the direct execution was withheld. This is supported by the hadith of Abu Sa'id, which mentions that Allah, the Almighty, will take a handful from the Fire after the intercession of prophets, angels, and believers, and bring out people who never did any good deed.