Hadith: Abu Jumu‘ah al-Ansāri once came to us and said: "We were with the Messenger of Allah (may Allah’s peace and blessings be upon him) and we were ten, including Mu‘ādh ibn Jabal. We said: 'O Messenger of Allah, is there anyone who will acquire greater rewards than ours?'"

عن ابن جُبير، قال: قَدِم علينا أبو جُمعة الأنصاري، قال: كنَّا مع رسول الله صلى الله عليه وسلم ومَعَنا معاذ بن جَبَل عاشرَ عشرةٍ فقلنا: يا رسول الله هل مِن أَحَدَ أعْظَمُ مِنَّا أجرًا، آمنَّا بك واتَّبَعْناك؟ قال: «وما يَمْنَعُكم من ذلك ورسولُ الله بيْن أَظْهُرِكم، يأتيكم بالوَحْي من السماء؟ بل قومٌ يأتون مِنْ بَعْدِكم يأتيهم كتابٌ بيْن لَوْحَيْن فيؤمنون به ويعملون بما فيه، أولئك أعظمُ منكم أجرًا».
[صحيح] - [رواه البخاري في خلق أفعال العباد والطبراني]

Ibn Jubayr reported: Abu Jumu‘ah al-Ansāri once came to us and said: "We were with the Messenger of Allah (may Allah’s peace and blessings be upon him) and we were ten, including Mu‘ādh ibn Jabal. We said: ‘O Messenger of Allah, is there anyone who will acquire greater rewards than ours? We believed in you and followed you.’ He said: ‘What prevents you from doing so, while the Messenger of Allah is among you, bringing you the revelation from heaven? There are people who will come after you and who will be given a book between two covers (the Qur’an), and they will believe in it and implement its commands. They have a greater reward than yours.'"
[Authentic hadith] - [Al-Bukhari in Khalq Af‘aal al-‘ibaad - At-Tabaraani]

Explanation

In this Hadīth, Abu Jumu‘ah al-Ansāri (may Allah be pleased with him) narrated that ten people, including himself and Mu‘ādh ibn Jabal, were accompanying the Messenger of Allah (may Allah’s peace and blessings be upon him) and they asked him if there were other Muslims who would acquire greater rewards than theirs (meaning: the Prophet's Companions), arguing that they believed in the Prophet (may Allah's peace and blessings be upon him) decisively and followed him firmly. The Prophet (may Allah's peace and blessings be upon him) told them that believing and following him was easier for them because he lived among them and brought them the revelation from heaven. The Prophet (may Allah's peace and blessings be upon him) added that there would be people who would get a greater reward, as they would come after the Companions to find just a book between two covers (the Qur’an), yet they would believe in it and implement its commandments. The meaning is that such Muslims will acquire a reward that is greater than the reward of the Companions (may Allah be pleased with them) only in this regard, even if the Companions surpassed them in other aspects, such as hard work and dedication in serving Allah and struggling for His cause. Thus, this Hadīth cannot be taken as proof that a Muslim who exists after the time of the Companions is better than the honorable Companions, as earning greater reward for some acts does not ensure absolute superiority. Ahl As-Sunnah wa al-Jamā‘ah believe that Companionship of the Prophet (may Allah's peace and blessings be upon him) is an unparalleled status, and that every Companion is better than any Muslim who comes after the Companions.