Likutei Halakhot, Choshen Mishpat, Laws of Gifting 4:11

11. And therefore Avraham Avinu (our father Avraham) did not wish to take the Me'arat HaMachpelah (Cave of Machpelah) as a gift from Efron, as it is written (Bereshit 23): "Let him give it to me for full price (kesef malei)." For because of the great intensity of the holiness that was there, when it was under the hand of Efron, the kelipot (husks that conceal holiness) surrounded it very greatly, and therefore with Efron there was darkness and gloom, as is brought. Therefore it was not possible to remove it from Efron as a gift, for free, but only for full price, because it is impossible to bring out and raise up holiness for free, especially such a lofty holiness. Therefore he gave him four hundred shekels of silver, which hint at the four hundred alemin dechisufin (worlds of longing), as is written in the holy Zohar. That is, because the money of Avraham was very holy, and all the elevated gevanin (colors/hues) were revealed through it, which are the greatness of the Borei yitbarach (Creator, blessed be He). This is the aspect of the four hundred worlds of longing in which the tzaddikim (righteous ones) delight, which are the aspect of the totality of all the holy colors, which everyone craves and delights to see and gaze upon. And this is the aspect of "four hundred shekels of silver, over l'socher (current among merchants)," and its Targum (Aramaic translation) renders: "that is accepted in commerce in every province" — that is, all the commerce and trade in every province is all done by means of silver (kesef), as it is written (Kohelet 10): "And money answers everything," because silver contains within it all the elevated colors that are included in the four hundred worlds of longing, which are the aspect of "four hundred shekels of silver." And by this power Avraham acquired the Me'arat HaMachpelah from Efron, by revealing the greatness of the Creator through his four hundred shekels of silver, in which all the colors, etc., were included, as above. Through this the kelipot that wished to cling there were subdued, and they fell and were nullified, and the field and the cave rose up and were acquired by Avraham, as it is written: "And the field of Efron rose [vayakam]" — "it had a rising [tekumah]," as Rashi explains there — and all this through the revelation of the colors that were in the silver of Avraham, as above. But certainly Efron did not merit to enjoy these colors, for afterward, when the silver came into his hand, the colors — which are the aspect of the four hundred worlds of longing — became hidden, as explained above.

Similarly, David did not want to accept the threshing floor of Aravnah for free, because that was the site of the Beit HaMikdash (Holy Temple), where it was impossible to extract from the sitra achra (the "other side," i.e., the realm of impurity) for free, but only with full payment of silver, in order to subdue the kelipot that surrounded it, through the revelation of the hues contained in silver and gold, as mentioned above. This is why silver and gold are mentioned there regarding David, as it is written in Divrei HaYamim (Chronicles) (I 21): "for full silver... and David gave... shekels of gold," because there it was necessary to raise up holiness to the highest degree, since that was the site of the Beit HaMikdash and the Beit Kodshei HaKodashim (House of the Holy of Holies). Therefore it was necessary to reveal all the hues contained in the silver and gold, in order to subdue the kelipot that surrounded that place—for the higher the holiness, the more the kelipot surround it there. Correspondingly, one must draw forth the revelation of the hues even more, in order to subdue them and nullify them through this, as mentioned above.