Hadith No: 1
Al-Haythami - Majma' al-Zawa'id wa Manba' al-Fawa'id
Book of Hajj - Chapter on Placing the Face on the Grave of our Master, the Messenger of Allah (peace be upon him and his holy progeny)
Volume: (4) - Page Number: (2)
5845 - Narrated from Abu Dawood ibn Abi Salih, who said: "One day, Marwan approached and found a man with his face placed on the grave. He said: 'Do you know what he is doing?' Then he turned to him and found it was Abu Ayyub. Marwan continued, 'Yes, I came to see the Messenger of Allah (peace be upon him and his holy progeny) and I did not see the stone.'" This account is fully detailed in the Book of Caliphate. Ahmad and Dawood ibn Abi Salih narrated it. Al-Dhahabi said: "None narrated it from him except al-Walid ibn Kathir," and Many ibn Zayd narrated it from him as mentioned in the Musnad, and no one weakened him.

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Reference: Majma al-Zawaaed wa Mamba' al-Fawaaed Book 4

Hadith No: 2
Al-Heithami - Majma' az-Zawa'id wa Manba' al-Fawa'id
Book of Caliphate - Chapter on Appointing Those Unfit to Positions
Volume: (5) - Page Number: (245)
[The text is lengthy, so only the relevant excerpt is provided here]
9252 - Narrated from Dawood ibn Abi Salih, who said: "One day, Marwan approached and found a man placing his face on the grave. He said: 'Do you know what he is doing?' He then came closer, and behold, it was Abu Ayyub. Marwan said: 'Yes, I came to the Messenger of Allah (peace be upon him and his holy progeny) and did not come to the stone.' I heard the Messenger of Allah (peace be upon him and his holy progeny) say: 'Do not weep for the religion when its people are in charge, but weep for the religion when others unfit are in charge.'" Ahmad and al-Tabarani narrated this in the large and medium collections, and in it is Kathir ibn Zayd, whom Ahmad and others deemed trustworthy, while an-Nasa'i and others deemed him weak....

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Reference: Majma al-Zawaaed wa Mamba' al-Fawaaed Book 5