We discussed among ourselves which of us would go to the Messenger of Allah ﷺ and ask him which deeds are most beloved to Allah the Exalted, but none of us stood up to do so. Then the Messenger of Allah ﷺ sent a man to us who gathered us together, and he recited to us this entire surah, meaning Surah as-Saff.
حدثنا يحيى بن آدم حدثنا ابن المبارك عن الأوزاعي عن يحيى بن أبي كثير عن أبي سلمة وعن عطاء بن يسار عن أبي سلمة
تذاكرنا أيكم يأتي رسول الله ﷺ فيسأله أي الأعمال أحب إلى الله تعالى فلم يقم أحد منا فأرسل إلينا رسول الله ﷺ رجلا فجمعنا فقرأ علينا هذه السورة يعني سورة الصف كلها
Its isnad is sahih, its narrators are trustworthy and well known, and it is found in Tirmidhi 5/412, no. 3309, where he pointed out the disagreement over the isnad. He means the following hadith. It is also found in Darimi 2/263, no. 2390. Hakim graded it sahih 2/487, and Dhahabi agreed with him.