An important difference between Ahmadi Muslims and other Muslims is with regard to the interpretation and significance of the words ‘Khatamun Nabiyyeen’, which is a unique epithet of the Holy Prophet, may peace and blessings of Allah be upon him, mentioned in the Holy Qur'an (Chapter 33, verse 41). Ahmadis and non Ahmadis both believe the Holy Prophet, may peace and blessings of Allah be upon him, to be the ‘Khatamun Nabiyyeen’, but they differ in its interpretation. We will discuss this in detail later.
This phrase literally means, ‘Seal of the Prophets’. The holy founder of the Ahmadiyya Community explained the beliefs of Ahmadis:
“My belief that I hold in this life and with which by the Grace of Allah, I shall pass on from this world, is that our Lord and Master, Muhammad Mustafa, peace and blessings of Allah he upon him, was Khatamun Nabiyyeen and the best of Messengers”
Hadhrat Mirza Ghulam Ahmad - Izala Auham p137
“...He was not the ‘Khatamul Ambiya’ in the sense that no blessing would henceforth accrue to anyone. He is ‘Khatamul Ambiya’ in the sense that no blessing can accrue to anyone without his seal, and as for his ’Ummah’ (his followers), the door of converse with God the Almighty is open for them till the Day of Resurrection; it will never be closed. No other Prophet is the possessor of the ‘Seal’; it is only he who possesses the ‘Seal’ which grants Prophethood - of course that Prophethood for which it is essential that one should be ‘Ummati’ too (ie. from among the Muslim Ummuh and a follower of the Holy Prophet)”
Hadhrat Mirza Ghulam Ahmad - Haqeeqatul-Wahy p27
"I proclaim that the spiritual influence of the eternal Prophethood of the Holy Prophet, may peace and blessings of Allah be upon him, has raised the Promised Messiah after the passage of thirteen centuries, from among his own Ummah, and with the impress of the same ‘Seal’ that had been granted to him”
Hadhrat Mirza Ghulam Ahmad - Al-Hakam June 10, 1905