Hadith: The Messenger of Allah (may Allah's peace and blessings be upon him) informed us of what was and of what is to come. The most knowledgeable among us is the one who memorized it best

عن أبي زيد عمرو بن أخطب الأنصاري رضي الله عنه : صلى بنا رسول الله صلى الله عليه وسلم الفجر، وصعد المنبر، فخطبنا حتى حضرت الظهر، فنزل فصلى، ثم صعد المنبر فخطبنا حتى حضرت العصر، ثم نزل فصلى، ثم صعد المنبر فخطبنا حتى غربت الشمس، فأخبرنا بما كان وبما هو كائن، فأَعْلَمُنَا أَحْفَظُنَا.
[صحيح] - [رواه مسلم]

Abu Zayd ‘Amr ibn Akhtab al-Ansāri (may Allah be pleased with him) reported: The Messenger of Allah (may Allah’s peace and blessings be upon him) led us in the dawn prayer, then ascended the pulpit and addressed us until the time for the noon prayer arrived. He then came down, prayed, then ascended the pulpit and addressed us until the time for the afternoon prayer arrived. He then came down, prayed, then ascended the pulpit and addressed us until sunset. He informed us of what was and of what is to come. The most knowledgeable among us is the one who memorized it best.
[Authentic hadith] - [Narrated by Muslim]

Explanation

The Companion ‘Amr ibn Akhtab (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) once gave a whole-day sermon. He performed the Fajr prayer then ascended the pulpit and addressed them until it was time for the Zhuhr prayer. He came down, performed the Zhuhr prayer then ascended the pulpit and spoke until it was time for the ‘Asr prayer. He came down, performed the ‘Asr prayer then ascended the pulpit and spoke until sunset (the time for the Maghrib prayer). His sermon lasted the whole day from dawn to sunset. On that day, Allah, the Exalted, imparted to him some knowledge about the unknown events of the past and the future. So the Prophet (may Allah's peace and blessings be upon him) informed his Companions of what he had learned. The most knowledgeable of them were those who memorized well what they heard from him that day.