What is ‘it’ in Galatians 3:6?

Gal 3:6 Even as Abraham believed God, and it was accounted to him for righteousness.
Gal 3:7 Know ye therefore that they which are of faith, the same are the children of Abraham.
Gal 3:8 And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, In thee shall all nations be blessed.
Gal 3:9 So then they which be of faith are blessed with faithful Abraham.