His boss 'assured' him that he had her continued support. = His boss 'assured' him of her continued support. = “You have my continued support,” his boss 'assured' him.
You can 'rest assured' [=you can be sure] that these mistakes won't happen again. = 'Rest assured', these mistakes won't happen again.
They are not 'assured of' being paid. [=it is not certain that they will be paid]
(..) "Hold still"? Match: Mr. Incredible. Room is secure. Commence message. Hello, Mr. Incredible. Yes, we know who you are. Rest assured, your secret is safe with us. My name is Mirage. We have something in common. According to the government, neither of us exist. (..)2004 The Incredibles