Midrash for Genesis 34:9

He gives wisdom to one who possesses wisdom and understanding and knowledge in all kinds of work. Similarly, you find that this was so in the case of Joshua: Joshua the son of Nun was full of the spirit of wisdom (Deut. 34:9), for he already possessed wisdom. This may be compared to a shopkeeper to whom a man goes to purchase wine, honey, oil, or brine. The shopkeeper smells the odor that comes from the bottle, and if it is of wine he pours wine into it, and he does likewise with honey, oil, or brine. When the Holy One, blessed be He, observes that a man has the spirit of wisdom within him, He fills him with additional wisdom. Hence He hath filled him with the spirit of wisdom, since he already possesses some.

The Temple was similarly constructed by means of these three attributes, as it is said: He was the son of a widow of the tribe of Naphtali, and his father was a man of Tyre, and he was filled with wisdom, understanding, and skill (I Kings 7:14). Similarly, the Temple will be rebuilt in the future with these three attributes, as is said: Through wisdom is a house builded, and by understanding it is established; and by knowledge are the chambers filled with all precious and pleasant riches (Prov. 24:3–4). Therefore, And He hath filled him with the spirit of God. Where did all this wisdom come from? From the spirit of God. And He filled him with the spirit of God alludes also to Joshua, who descended from the tribe of Ephraim, as it is written: And Joshua the son of Nun was full of the spirit of wisdom (Deut. 34:9). And it refers as well to Othniel the son of Kenaz, who came from the tribe of Judah, since it is written about him: And the spirit of the Lord came upon him, and he judged Israel (Judg. 3:10). All this happened because Moses blessed the tribe: And this for Judah, and he said: “Hear, Lord, the voice of Judah, and bring him in unto his people; his hands shall contend for him, and Thou shalt be a help against his adversaries” (Deut. 33:7). When they become involved in difficulties, You shall be a help to them.

There is wisdom which is both beneficial and harmful to the one who possesses it. Joshua possessed wisdom that was beneficial, as it is said: Joshua the son of Nun was full of the spirit of wisdom (Deut. 34:9). To what may this be compared? To a reservoir that supplied an entire city with water. Everyone praised it, with the exception of one man who advised them to praise the well that supplied the water (for the reservoir) instead. Similarly, while they were extolling Joshua for giving drink to Israel through his wisdom, he said to them: “Praise Moses instead,” for Moses had laid his hands upon him (ibid.). Balaam had wisdom which was harmful to him, as it is stated: The saying of him who heareth the word of God, and knoweth the knowledge of the Most High (Num. 24:23), and finally: Balaam the son of Beor they slew with a sword (ibid. 31:8).