Riyad as-Salihin 971
Jabir (May Allah be pleased with him) reported:
The Messenger of Allah (ﷺ) 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. [Abu Dawud] .
وعنه قال‏:‏ كان رسول الله صلى  الله عليه وسلم  يتخلف في المسير، فيزجي الضعيف ويردف ويدعو له، ‏(‏‏(‏رواه أبو داود بإسناد حسن‏)‏‏)‏‏.‏