"Apply your heart to discipline and your ears to words of knowledge"
The context of these verses is the negative of trying to gain through cheating orphans and the oppressed. The idea here is do not try and build up your portfolio through cheating and oppressing others – especially those who are the most vulnerable – for God will be the avenger of these people.
Instead of cheating your way to wealth and prosperity, instead focus your soul on instruction and discipline and make sure that you do not get side-tracked by fancy myths, legends, and stories. Take in real knowledge, not fanciful brain candy that really gives no nourishment