The context makes it clear that miserliness with knowledge is the chief matter in view. In several other verses as well He censures them for hiding knowledge, such as His words:

“When God took the covenant of those who had been given the Scripture: ‘You shall make it clear to mankind and not conceal it.’” (Āl ʿImrān 3:187)

and His words:

“Those who conceal what We have sent down of clear proofs and guidance after We have made it evident for mankind in the Book—such people are cursed by God and cursed by those who curse, except those who repent …” (al-Baqarah 2:159-160)

and His words:

“Indeed, those who conceal what God has sent down of the Book and barter it for a paltry price—they consume nothing in their bellies but fire.” (al-Baqarah 2:174)

And the Exalted says:

“When they meet those who believe, they say, ‘We believe,’ but when they are alone with one another they say, ‘Will you tell them what God has disclosed to you so that they may use it as an argument against you before your Lord? Will you not reason?’” (al-Baqarah 2:76)

Thus He portrays those who incurred wrath as concealing knowledge: sometimes out of sheer miserliness, sometimes trading its disclosure for worldly position or wealth, and sometimes out of fear that what they reveal may later be used as evidence against them.