It was narrated that Zayd ibn Thabit (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings of Allah be upon him) say, “May Allah bless a man who hears a hadeeth from us and memorizes it so that he can convey it to others, for perhaps he is conveying it to one who will understand it better than him, and perhaps the one who conveys knowledge does not understand it himself.” (Narrated and classed as hasan (sound) by al-Tirmidhi, 2656; also narrated by Abu Dawood. 3660; Ibn Majah, 230).
Al-Mubarakfoori said: What is meant is that Allah has singled him out for happiness and joy because of the knowledge with which He has blessed him and the status among people in this world and blessings in the Hereafter that he attains thereby, so that the joy and blessings are seen on his face. And it was suggested that the hadeeth indicates what happens to the person of joy and blessing that appears on his face. Tuhfat al-Ahwadhi, 7/347, 348
Imam Nawawi's 40 Hadith have come to be known as the most comprehensive, and holistic, compilation/collection of hadith of the Prophet Muhammad (peace and blessings of Allah be upon him) that convey the essence of Islam.
A Website that offers authentic translation, commentary, and a brief video explanation of the Forty Hadeeth Nawawi:
A PDF book of explanation:
https://ahadith.co.uk/downloads/Commentary_of_Forty_Hadiths_of_An-Nawawi.pdf