The Prophet ﷺ noticed his companions hanging back, so he said, "Come forward and follow my lead, and let those behind you follow yours. People will keep falling behind until Allah casts them behind on the Day of Resurrection."
حدثنا يزيد أخبرنا أبو الأشهب عن أبي نضرة
رأى النبي ﷺ في أصحابه تأخرا فقال تقدموا فأتموا بي وليأتم بكم من بعدكم لا يزال قوم يتأخرون حتى يؤخرهم الله عز وجل يوم القيامة
Its isnad is sahih. Yazid is Ibn Harun, and Abu Jafar the perfume seller is Jafar bin Hayan, who is trustworthy. The hadith is found in Muslim 1/325, no. 438, in the Book of Prayer, chapter on straightening the rows, and in Abu Dawud 1/181, no. 680, in the Book of Prayer, chapter on the row of women, and in Nasai 2/83, no. 795.