He would memorize the statements of the Prophet (peace be upon him) for the Muslims.
al-Hafidh Ibn Hajar (may Allah have Mercy on him) said:
“He[Bukhari] did not include in this chapter(memorization of knowledge) anything regarding anyone but Abu Hurayrah[RA], and this isbecause he was the Companion who memorized the most hadith. ash-Shafi’i said: “Abu Hurayrah[RA] memorized the most out of all the narrators of his time.” And Ibn ‘Umar[RA] stood at
his funeral, invoking Allah’s Mercy for him, saying: “He would memorize the statements of
the Prophet (peace be upon him) for the Muslims.””
Fath al-Bari’ (1/258)