Tafsiran Bilangan 27:17: Rashi, Sforno, Siftei Chakhamim & Rav Hirsch

אשר יצא לפניהם ONE WHO MAY GO BEFORE THEM — not as is the way of the kings of the nations who sit at home and send their armies to battle, but as “I” have done — I who fought against Sihon and against Og, as it is said, (Numbers 21:34) “Do not fear him: “[for I have delivered him into thy hand … and thou shall do to him as thou didst unto Sihon, etc.]” and as is the way that Joshua followed, as it is said, (Joshua 5:3) “And Joshua went to him and said, Art thou for us [or for our adversaries]”. And so, too, in the case of David, it says, (I Samuel 18:16) “For he went out and came in before them” — went out at their head, and came in at their head (Sifrei Bamidbar 139:2).

אשר יצא לפניהם, when they would go to war;

Another interpretation [of “and bring them in”]: That You will not treat him in the way You treat me. According to the first reason there is the difficulty as to why it states, “And who will lead them out” for what merit is needed for leading out? It is understandable that to bring them in requires merit that they not perish, [but regarding leading them out there is a difficulty]. Therefore Rashi brings the other interpretation. And according to the second interpretation there is the difficulty that, “Who would lead them out” is not the same as, “Who will go forth before them.” There, his main prayer was for the people, while, “Who would lead them out” is explained as his prayer for the benefit of the leader. Since the vav conjunctive in ואשר יוציאם ["and who would lead them out"] implies that his prayers were [also] entirely for the benefit of Yisroel, Rashi also brings the first reason.

ואשר יוציאם AND WHO WILL LEAD THEM OUT, safely through his merits,

ואשר יביאם AND WHO WILL BRING THEM IN, safely through his merits (Siphre). Another explanation: ואשר יביאם AND WHO WILL BRING THEM IN — I ask that You should not do to him, as You have done to me' for I may not bring them into the Land. (cf. Yalkut Shimoni on Torah 776).