The Messenger of Allah ﷺ noticed his companions hanging back, so he said to them, "Come forward and follow my lead, and let those behind you follow yours. People will keep lagging behind until Allah puts them behind."
أن رسول الله ﷺ رأى في أصحابه تأخرا. فقال لهم: تقدموا فائتموا بي، وليأتم بكم من بعدكم، لا يزال قوم يتأخرون حتى يؤخرهم الله.
Muslim narrated it in the Book of Prayer (438), from Shayban bin Farroukh, from Abu Ashhab, from Abu Nadra Abdi, from Abu Saeed, who related the same account. In another version, he saw a group of people at the back of the masjid, and he related the same account.As for his saying, "until Allah pushes them back," it means away from His mercy, or from His great favor, or from an elevated rank.Abu Ashhab's name was Jafar bin Hayan Saadi Atardi, and Abu Nadra's name was Mundhir bin Malik Abdi.