Whenever the Messenger of Allah ﷺ sent off an army, once they reached Uqba al-Wada, he would say, "I entrust to Allah your religion, your trust, and the final outcomes of your deeds."
كان رسول الله ﷺ إذاشيع جيشا فبلغ عقبة الوداع قال: أستودع الله دينكم، وأمانتكم وخواتم أعمالكم.
Reported by Abu Dawud (2601), Nasai in Kubra (10288, and this is his wording), and Hakim (2/97-98), all through Hammad bin Salama, from Abu Jafar Khatmi, from Muhammad bin Kaab, from Abdullah Khatmi, who said, and then he related it. Its isnad is sahih.As for what was reported from Muaz bin Anas as a raised report (marfu), "That I accompany a mujahid in the path of Allah and take care of his mount for a morning or an evening is dearer to me than the world and everything in it," its isnad is daif. It was reported by Ibn Majah (2824) and Ahmad (15643) through Ibn Lahia, from Zabban bin Fayd, from Sahl bin Muaz bin Anas, from his father, and then he related it. Its isnad is daif because of the weakness of Ibn Lahia and Zabban bin Fayd, and Busiri attributed its fault to these two in Misbah Zujaja (3/167).Hakim (2/98) also reported it, and Bayhaqi (9/173) reported it from him, through Yahya bin Ayub, from Zabban, with the same wording, and he said, "Its isnad is sahih." I say, its fault is Zabban, who is weak in hadith by agreement of the scholars, and he used to report objectionable narrations (manakir) from Sahl bin Muaz.As for the wording "akiffuhu," this is how it appears in Sunan Ibn Majah, while in the Musnad it is "fa akatifuhu," and in Sunan al-Kubra it is "fa aknifuhu." What is meant in any case is helping the mujahid in the path of Allah.