The vessels of the Pool of al-Kawthar are more numerous than the stars

It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that he said: Hamzah bin Abd al-Muttalib (may Allah be pleased with him), the paternal uncle of the Messenger of Allah (peace and blessings be upon him), was martyred (at the Battle of Uhud) while he was in a state of janabah (major ritual impurity). Then the Messenger of Allah (peace and blessings be upon him) said: "The angels have washed him."
This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.

It is narrated from Sayyiduna Usamah bin Zayd (may Allah be pleased with them both) that he said: The Messenger of Allah (peace and blessings be upon him) set out intending to go to the house of Sayyiduna Hamzah, and I followed him until he stopped at the door and said: "Peace be upon you. Is Abu Umarah at home?" The narrator says: His wife said: "No, by Allah, may my father and mother be sacrificed for you! He went out towards you; I think he missed you in one of the lanes of Banu al-Najjar. O Messenger of Allah, may my father and mother be sacrificed for you, will you not come in?" He (peace and blessings be upon him) asked: "Do you have anything (to eat)?" She said: "Yes." So he (peace and blessings be upon him) went in, and she placed before him a qa'b (wooden bowl) containing hays (a sweet made of dates, ghee and dried curd). She said: "O Messenger of Allah, may my father and mother be sacrificed for you, eat it; may it be pleasant and wholesome for you. You have come when I myself wanted to come to you and congratulate you, for Abu Umarah told me that you have been given a river in Paradise called al-Kawthar." Then the Messenger of Allah (peace and blessings be upon him) said: "And its vessels (for drinking) are more numerous than the stars of the sky, and the most beloved to me of those who come to me there are your people."
This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.

It is narrated from Sayyiduna Anas (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) passed by Sayyiduna Hamzah on the day of the Battle of Uhud, when his nose and ears had been cut off and his body had been mutilated. He (peace and blessings be upon him) said: "Were it not for fear of the grief of Safiyyah (the sister of Sayyiduna Hamzah), I would have left him (on this very field) until Allah Almighty gathers him from the bellies of the birds and the beasts." Then he (peace and blessings be upon him) shrouded him in a namirah (a striped cloak).
This hadith is sahih (authentic) on the condition of Imam Muslim, but the two Shaykhs (Bukhari and Muslim) did not record it.

It is narrated from Sayyiduna Jabir bin Abdullah (may Allah be pleased with them both) that he said: A son was born to a man among us, and the people asked: "What shall we name him?" The Prophet (peace and blessings be upon him) said: "Name him with the name that is the most beloved of all names to me: Hamzah bin Abd al-Muttalib."
This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.

It is narrated from a man of Madinah that he said: My grandfather brought my father to the Messenger of Allah (peace and blessings be upon him) and said: "This is my son; what shall I name him?" He (peace and blessings be upon him) said: "Name him after the person who is the most beloved of all people to me: Hamzah bin Abd al-Muttalib."
This unknown narrator fell short in narrating the hadith from Ibn Uyaynah, and the correct report in this matter is that of Ya'qub bin Humayd. Abu Ahmad al-Hafiz used to debate with me, holding that Bukhari narrated from him in his al-Jami' al-Sahih, while I used to deny it.

It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Last night I entered Paradise, and there I saw Ja'far (al-Tayyar) flying with the angels, and Hamzah reclining on a couch."
This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.