I don't know which version that came from, tbh, so I've gone and removed it from my post. Thanks for catching that!
So Satan knows who has faith and who doesn't? He knows our hearts?
I don't think he knows our hearts, but he tests the faith of professing believers, sometimes severely with God's permission as he did with Job. The point of that book is that true faith perseveres:
Job 1:8 And the LORD said to Satan, “Have you considered my servant Job, that there is none like him on the earth, a blameless and upright man, who fears God and turns away from evil?”
Job 1:9 Then Satan answered the LORD and said, “Does Job fear God for no reason?
Job 1:10 Have you not put a hedge around him and his house and all that he has, on every side? You have blessed the work of his hands, and his possessions have increased in the land.
Job 1:11 But stretch out your hand and touch all that he has, and he will curse you to your face.”