None resembled the Prophet (ﷺ) more than Al-Hasan bin `Ali did.
Sahih al-Bukhari Book 62, Hadith 97
← Previous Hadith Abu Bakr used to say, "Look after Muhammad (ﷺ) in (looking after) his family."

Sahih al-Bukhari Book 62, Hadith 96 Next Hadith → A person asked `Abdullah bin `Umar whether a Muslim could kill flies. I heard him saying (in reply). "The people of Iraq are asking about the killing of flies while they themselves murdered the son of the daughter of Allah's Messenger (ﷺ) . The Prophet (ﷺ) said, They (i.e. Hasan and Husain) are my two sweet basils in this world."

Sahih al-Bukhari Book 62, Hadith 98