Abu Ahwas reported,

We were at Abu Musa's house with a group of Abdullah's companions, and they were examining a copy of the Quran. Abdullah stood up to leave, and Abu Masud said, "I do not know that the Messenger of Allah ﷺ left behind anyone more knowledgeable about what Allah revealed than this man who has just stood up."Abu Musa replied, "If you say that, indeed he used to be present when we were absent, and he was granted entry when we were kept out."

Muslim 6330

Sahih

حدثنا أبو كريب محمد بن العلاء حدثنا يحيى بن آدم حدثنا قطبة هو ابن عبد العزيز عن الأعمش عن مالك بن الحارث

عن أبي الأحوص قال

كنا في دار أبي موسى مع نفر من أصحاب عبد الله وهم ينظرون في مصحف فقام عبد الله فقال أبو مسعود ما أعلم رسول الله ﷺ ترك بعده أعلم بما أنزل الله من هذا القائم فقال أبو موسى أما لئن قلت ذاك لقد كان يشهد إذا غبنا ويؤذن له إذا حجبنا

مسلم 6330صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Muslim
Book
Virtues of the Companions, may Allah be pleased with them
Chapter
From the virtues of Abdullah bin Masud and his mother, may Allah be pleased with them
Numbering
Darussalam 6330
Muslim 6330