And were it not that the act occurs by the slave's will and choice, praising the doer of good would be futile, and punishing the wrongdoer would be injustice, and Allah the Exalted is free from futility and injustice.

The Shaykh :"And were it not that the act occurs by the slave's will and choice, praising the doer of good would be futile, and punishing the wrongdoer would be injustice". Correct? Good.
This is also regarding punishment and reward. If we said that the doer of good acts without will and without choice, then praising him would be futile. Are you praising him for something he did not do by his own choice?
Likewise, punishing the wrongdoer would be injustice, because you are punishing him for something he cannot escape, and that is injustice.
Therefore, the Jabriyyah said that Allah the Exalted has the right to punish the best of people and the most devout of people; He has the right to punish him, and His punishment is not injustice. Why, my brothers, is it not injustice? Allah says: They said: But this is injustice. Why? He said: Are not all of creation the servants of Allah? Our answer: Yes. So He has the right to do with His servants whatever He wills. We say: Yes, He has the right to do whatever He wills, but He has forbidden injustice for Himself.