This is a strange hadith, and its chain of transmission is not strong. Ka'b is not well-known, and we do not know of anyone who narrated from him other than Layth ibn Abi Sulaym.

3940 - Muhammad ibn Bashshar narrated to us, saying: Abu 'Amir al-'Aqadi narrated to us, saying: Zuhayr ibn Muhammad narrated to us, from 'Abdullah ibn Muhammad ibn 'Aqil, from al-Tufayl ibn Ubayy ibn Ka'b, from his father, that the Messenger of Allah, peace and blessings be upon him, said: "My likeness among the prophets is like a man who built a house, and perfected it, completed it, and beautified it, but left in it the place of one brick. The people began to walk around the building, marveling at it, and saying: 'If only the place of that brick were completed.' And I, among the prophets, am the place of that brick."

3941 - And by the same chain of transmission, from the Prophet, peace and blessings be upon him, who said: "When the Day of Resurrection comes, I will be the leader of the prophets, and their speaker, and the one who holds their intercession, without pride."

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And it is supported by the hadith of 'Abdullah ibn 'Amr that follows with the compiler at number (3943), and its chain of transmission is authentic.

(1) Authentic due to corroborating evidence, and this chain of transmission is good in follow-ups and supporting witnesses because of 'Abdullah ibn Muhammad ibn 'Aqil.
It is in the "Musnad" of Ahmad (21243).
It is supported by the hadith of Abu Hurayrah in Ahmad (7322), which is in the Two Sahihs, and we have mentioned the rest of its supporting witnesses there.

(2) Authentic due to corroborating evidence, and its chain of transmission is like the previous one.
It was also recorded by Ibn Majah (4314), and it is in the "Musnad" (21245).