Midrash sur Les Nombres 32:24

"And much cattle" (Numbers 32:1). This is [the meaning of] that which is stated by the verse (Ecclesiastes 10:2), "A wise man’s heart is to his right," that is Moshe; "but a fool’s heart is to his left," that is the Children of Reuven and the Children of Gad, who made the essential, secondary, and the secondary, essential. Why? Because they loved their possessions more than their selves. As they said to Moshe (Numbers 32:16), "'We will build here sheepfolds for our flocks,' first, and afterwards, 'and towns for our children.'" Moshe said to them, "Do not do like this, make the essential first; 'build towns for your children,' and afterwards 'sheepfolds for your flocks' (Numbers 32:24)." Hence, "A wise man’s heart is to his right," that is Moshe; "but a fool’s heart is to his left," that is the Children of Reuven and the Children of Gad. The Holy One, blessed be He, said to them, "You loved your money more than your souls. By your lives, there is no blessing in this, as stated (Proverbs 20:21), 'An estate acquired in haste at the outset will not be blessed in the end.'" "Do not toil to gain wealth; have the sense to desist" (Proverbs 23:4). And who is wealthy? One who is happy with his lot, as stated (in Psalms 128:2), "You shall eat the produce of your hands; you shall be happy, and it shall go well with you."

Another interpretation of "And much cattle" (Numbers 32:1). This is [the meaning of] that which is stated by the verse (Ecclesiastes 10:2), "A wise man’s heart is to his right," that is the good impulse; "but a fool’s heart is to his left," that is the evil impulse. Another interpretation: "A wise man’s heart is to his right," that is the righteous who put their hearts to Torah which is from the right, as it is stated (Deuteronomy 33:2), “from His right, a fiery law to them; "but a fool’s heart is to his left," that is the evildoers who put their hearts to becoming rich, as it is stated (Proverbs 3:16), “in her left, riches and honor.” Another interpretation: "A wise man’s heart is to his right," that is Moshe; "but a fool’s heart is to his left," that is the Children of Reuven and the Children of Gad, who made the essential, secondary, and the secondary, essential. Why? Because they loved their possessions more than the [human] souls. As they said to Moshe (Numbers 32:16), "'We will build here sheepfolds for our flocks, and towns for our children.'" Moshe said to them, "This is nothing; rather make the essential, essential. First 'build towns for your children,' and afterwards 'sheepfolds for your flocks' (Numbers 32:24)." Hence, "A wise man’s heart is to his right," that is Moshe; "but a fool’s heart is to his left," that is the Children of Reuven and the Children of Gad. The Holy One, blessed be He, said to them, "You loved your money more than [your] souls. By your lives, there is no blessing in this, as stated (Proverbs 20:21), 'An estate acquired in haste at the outset will not be blessed in the end.'" And it likewise states (Proverbs 23:4), "Do not toil to gain wealth; have the sense to desist." And who is wealthy? One who is happy with his lot, as stated (in Psalms 128:2), "You shall eat the produce of your hands; you shall be happy, and it shall go well with you."