وعنه قال: كان رسول الله صلى الله عليه وسلم يتخلف في المسير، فيزجي الضعيف ويردف ويدعو له
The Messenger of Allah (sallallahu alayhi wa sallam) used to lag behind while travelling and urge the weak to walk quickly. He used to take up someone behind him and make supplication for him.
Riyad as-Salihin 971, Book 8, The Book of Etiquette of Traveling, Hadith 16. 1 min read