Sign of Faith or Faithfulness? (Romans 4:11 (LD 27; BC Article 34)

Many times people will say that the sacraments are a sign of our faith.  We might not think that it is important to see that sacrament is a sign of God’s faithfulness verses the sign being a sign of my faith.  Ultimately we need to look discussion in light of the covenant of grace.  Did Abraham receive the sign because of his faith or because of the Lord’s faithfulness?  In other words does the sign point to Abraham’s faith or does it point to the promises of God and His faithfulness?  What does Paul say in Romans 4:11 regarding the sign that was given to Abraham?