Midrash sa Mga Bilang 27:18: Sefer HaYashar (midrash), Devarim Rabbah, Sifra & Midrash Tanchuma

At that time the Lord said unto Moses: Behold, the days are approaching for thee to die. Take ‎thou Joshua, the son of Nun, thy servant, and place him in the tabernacle that I may give him ‎my commandments, and Moses did so.‎‏ ‏And the Lord appeared in the tabernacle in a pillar of ‎cloud, and the pillar of cloud stood at the door of the tabernacle, and the Lord commanded ‎Joshua, the sun of Nun, saying unto him: Be thou strong and courageous for thou shalt bring ‎the children of Israel to the land which I have given unto them, and I will be with thee.‎‏ ‏And ‎Moses said unto Joshua: Be strong and courageous, for thou wilt cause the children of Israel to ‎inherit the land, and the Lord will be with thee, He will not leave thee nor forsake thee. Fear ‎not and be not dismayed.‎‏ ‏And Moses called to all Israel and he said unto them: Ye have seen ‎all the good which the Lord your God hath done for you in the wilderness. Now therefore ‎observe ye all the words of this law and walk in the way of the Lord your God, do not turn from ‎the path which the Lord hath commanded you, neither to the right nor to the left. And Moses ‎taught the child ren of Israel statutes, and judgments, and laws, to practice them in the land, ‎as the Lord had commanded him, behold they are written in the book of the law of God which ‎he gave unto the children of Israel by the hand of Moses. And when Moses had finished ‎instruct ing the children of Israel, the Lord said unto him: Go up to Mount Abarim and die ‎there, and thou shalt be gathered to thy people like unto Aaron, thy brother. And Moses went ‎up, as the Lord had commanded unto him, and he died there, in the land of Moab, in the ‎fortieth year of the children of Israel’s departure from the land of Egypt. And the children of ‎Israel wept for Moses in the plains of Moab, thirty days; so the days of mourning for Moses ‎were ended.‎

“At that time” – at what time? It was at the time that Joshua was appointed, as it is stated: “I commanded Joshua [at that time]” (Deuteronomy 3:21). Rav Huna said: When the Holy One blessed be He said to Moses: ‘Joshua’s tenure has arrived,’ at that moment Moses began asking for mercy to enter the land. To what is the matter comparable? To a governor who, during his tenure, would issue decrees and the king would fulfill them. He would redeem whom he wanted and imprison whom he wanted. When he was replaced and another was appointed in his stead, he began asking the gatekeeper to enter, but he would not let him. So, Moses, all the days of his tenure he would imprison whom he wanted, as it is stated: “They, and everything that was theirs, descended alive [into the abyss]” (Numbers 16:33). He redeemed whom he wanted, as it is stated: “Let Reuben live and not die” (Deuteronomy 33:6). When he was replaced and Joshua was appointed in his stead, as it is stated: “Take to you Joshua son of Nun” (Numbers 27:18), he began pleading to enter the land. The Holy One blessed be He said to him: “It is enough for you” (Deuteronomy 3:26).

2) Variantly: "Take Aaron and his sons with him": What is the intent of this? In many places the "taking" of men is mentioned in respect to Moses, viz. (Numbers 3:41): "And you shall take the Levites for Me — I am the L–rd." (Numbers 11:16): "And you shall take them (the seventy elders) to the tent of meeting." (Numbers 1:17): "and Moses… took these men who were designated by name." (Numbers 27:18): "Take for yourself Joshua the son of Nun." Now did Moses "string men over his shoulders"? (The intent is that) the Holy One Blessed be He said to him: "Take" them with words so that their hearts not be tied to other things.