Albert Barnes Commentary Romans 4:7

"[saying], Blessed are they whose iniquities are forgiven, And whose sins are covered." — Romans 4:7 (ASV)

Blessed. Happy are they: they are highly favoured. (See Barnes on Matthew 5:3).

Whose sins are covered. This means they are concealed or hidden from view. God will no longer look upon these sins, and He will no longer remember them.

"By these words," says Calvin (on this passage), "we are taught that justification with Paul is nothing else but pardon of sin." The word cover here does not refer to the atonement but is expressive of hiding or concealing; that is, of forgiving sin.