Belief = Obedience

He who believes in the Son has eternal life; but he who does not obey the Son will not see life, but the wrath of God abides on him. John 3:36 NASB

He who believes in the Son has everlasting life; and he who does not believe the Son shall not see life, but the wrath of God abides on him. John 3:36 NKJV

Whoever believes in the Son has eternal life, but whoever rejects the Son will not see life, for God's wrath remains on him. John 3:26 NIV

I was reading the NRSV which is similar to the NASB and I came across John 3:36 and as you can see it says that he who does not obey the Son will not see life. Which seem to me to say that believeing is the same as obeying. Though it seems that it is not always the case but obeying is not always believeing but since you can't simply believe a command you need to obey a command to show that you believe it that belief in the commands of Jesus is obeying.