Ferrugem literally translates to "rust". It's an interesting and somewhat unexpected word to find in a song, especially in the context of a relationship.
In "Deus Tá Vendo," the lyric "30 ferrugem você traiu eu perdoei" (30 rusts, you betrayed, I forgave) suggests that the betrayals or issues in the relationship have accumulated over time, like rust corroding something. It implies a long history of damage and forgiveness, making it a unique metaphor for the wear and tear on a relationship.
Have you ever felt like someone was lying to you, but you couldn't prove it? In "Deus Tá Vendo," which means "God Is Watching," the singer confronts a partner who they know is being unfaithful. They tell their partner to stop lying because they already know the truth, and even if they can't see everything, God can. The lyrics mention specific clues, like finding a secret cell phone in the car and seeing an unusually high credit card bill, which have exposed the partner's deceit.
This isn't the first time this has happened. The singer mentions having forgiven their partner for cheating in the past, only to be betrayed again. Now, they've had enough. They warn their partner that they will eventually get what they deserve, a kind of karma where they will experience the same pain of loving someone who doesn't love them back. The core message is a powerful warning: you might be able to lie to people, but you can't hide the truth from a higher power.