What does the Bible say about being surety?

Proverbs 17:18 states that a man void of understanding becomes surety for his friend, suggesting that such a commitment is unwise. In a broader sense, this idea reflects our spiritual condition; we owe God everything and can provide nothing in return. Just as one might need a surety due to untrustworthiness or lack of resources, we too are incapable of repaying our debt to God. The more we try to pay Him back through our good works, the deeper into debt we fall, as our best efforts are tainted with sin.