I heard the Prophet ﷺ say, "Seek out the weak among you for me, for you are granted provision and victory only through your weak ones."
حدثنا أحمد بن محمد بن موسى حدثنا عبد الله بن المبارك قال أخبرنا عبد الرحمن بن يزيد بن جابر حدثنا زيد بن أرطاة عن جبير بن نفير
سمعت النبي ﷺ يقول ابغوني ضعفاءكم فإنما ترزقون وتنصرون بضعفائكم
Takhrij, its chain is sahih. Abu Dawud also narrated it in the book of jihad, chapter on gaining victory through lowly horses and the weak, no. 2594, and Nasai, no. 3181, from the hadith of Abdul-Rahman bin Yazid bin Jabir, with the same wording. Ibn Hibban graded it sahih, no. 1620, as did Hakim, 2/145.