This excerpt is taken from Sheikh Ghulam Mustafa Zaheer Amanpuri's book Khatm-e-Nubuwwat.
Seal of Prophethood
The Seal of Prophethood is evidence for the Finality of Prophethood, observe:
Sayyiduna Saib bin Yazid رضي الله عنه narrates:
نظرت إلى خاتم النبوة بين كتفيه، مثل زر الحجلة .
"I saw the Seal of Prophethood between the shoulders of the Prophet Muhammad صلی اللہ علیہ وسلم, it was like a pigeon’s egg."
Reference: (Sahih al-Bukhari: 5670, Sahih Muslim: 2345)
Hafiz Ibn Kathir رحمه الله (774 AH) writes:
من أحسن ما ذكره ابن دحية، رحمه الله، وغيره من العلماء قبله فى الحكمة فى كون الخاتم كان بين كتفي رسول الله صلى الله عليه وسلم، إشارة إلى أنه لا نبي بعدك يأتى من ورائك .
"Ibn Dahiya رحمه الله and other scholars before him have said a very beautiful thing, they say that the Seal of Prophethood between the shoulders of the Messenger of Allah صلی اللہ علیہ وسلم indicates that after the Messenger of Allah صلی اللہ علیہ وسلم no prophet will come."
Reference: (Al-Bidaya wa al-Nihaya: 438/8)
Allama Ibn Hubayra رحمه الله (560 AH) writes:
إنه خص بالخاتم بين كتفيه إشارة إلى أنه خاتم الأنبياء، ولذلك كان من ورائه؛ لأنهم ختموا به، فلم يبق وراءه غيره .
"The Seal of Prophethood between the shoulders is a special characteristic of the Noble Prophet صلی اللہ علیہ وسلم. It indicates that you صلی اللہ علیہ وسلم are the Seal of the Prophets. That is why the Seal of Prophethood was on the back of the Prophet صلی اللہ علیہ وسلم, through you the chain of the Prophets ended. Therefore, after you صلی اللہ علیہ وسلم no prophet remained."
Reference: (Al-Ifsaah 'an Ma'ani al-Sihah: 407/6)
