No one resembled the Prophet ﷺ more than Hasan bin Ali. A man was sitting with the Prophet ﷺ when his son came to him. He took the boy, kissed him, and sat him on his lap. Then his daughter came, and he took her and sat her down beside him.The Prophet ﷺ said, "Why did you not treat them equally?"
لم يكن أحد أشبه بالنبي ﷺ من الحسن بن علي، وكان رجل جالسا عند النبي ﷺ، فجاءه ولد له، فأخذه، وقبله، وأجلسه في حجره، وجاءت ابنة له، فأخذها، فأجلسها، فقال النبي ﷺ: فهلا عدلت بينهما.
Tahawi narrated it in Sharh Maani al-Athar (4/89) through Yaqub bin Humayd bin Kasib, and Bayhaqi narrated it in Shuab (10510, 8327) through Ibrahim bin Munzir, and Yaqub bin Humayd, both of them from Abdullah bin Muaz, from Mamar, from Zuhri, from Anas, and he mentioned it.Bazzar narrated it (6361), saying, one of our companions narrated to us, from Abdullah bin Musa, from Mamar, from Zuhri, from Anas, leaving his shaykh unnamed. Haythami pointed to this in Majma (8/156), saying, "Bazzar narrated it and said, one of our companions, without naming him, and the rest of its narrators are trustworthy."As for his statement, "Abdullah bin Musa," this is a distortion, and the correct form is "Abdullah bin Muaz," as found in the other sources. Its chain is hasan because of Abdullah bin Muaz Sanaani, the companion of Mamar, for he is hasan al-hadith.The first part of the hadith, namely his statement, "No one resembled the Prophet ﷺ more than Hasan bin Ali," was narrated by Bukhari (3752) through another route from Mamar, from Zuhri, from Anas.The second part was added by Abdullah bin Muaz Sanaani, who was declared trustworthy by Ibn Main, Bukhari, and Muslim. His student Hisham bin Yusuf said, "He is truthful," and Ibn Adi said, "I hope he is not problematic." Someone of his standing, when he narrates a hadith with an addition that is not contradictory and contains nothing objectionable, has his addition accepted by the majority of hadith scholars.As for Daraqutni, he held that this addition should be considered defective, as stated in his Ilal (2609).