Why did God permanently set hypocrisy deep in their hearts of some people?

Verses 75-77 of Chapter 9:

There are some among them, who made this covenant with Allah: If He gives us of His bounty, we will disburse charity and lead a righteous life." But when Allah enriched them by His bounty, they grew niggardly and went back on their covenant, and paid no heed to it. As a consequence of the breach of the covenant they had made with Allah and the lies they told, He set hypocrisy deep in their hearts that will follow them till the Day when they shall meet Him.