What is the scriptural basis for "Love God and do whatever you please"? This quote has been attributed to St. Augustine, referring to what he said in a sermon on 1 John 4:4-12:


  See what we are insisting upon; that the deeds of men are only discerned by the root of charity. For many things may be done that have a good appearance, and yet proceed not from the root of charity. For thorns also have flowers: some actions truly seem rough, seem savage; howbeit they are done for discipline at the bidding of charity. Once for all, then, a short precept is given you: Love, and do what you will: whether you hold your peace, through love hold your peace; whether you cry out, through love cry out; whether you correct, through love correct; whether you spare, through love do you spare: let the root of love be within, of this root can nothing spring but what is good.


It's been paraphrased as:


  Love God and do whatever you please: for the soul trained in love to God will do nothing to offend the One who is Beloved.


I've heard people just use the first half without the full expression, usually in a flippant way, but I think Augustine may be onto something here.   We certainly get enough discussion about what God wants us to do or things along that line. Augustine seems to think that if we love God we aren't going to offend him and so don't need any "rules". Jesus seems to me to agree with him when he said:


  Master, which is the great commandment in the law? Jesus said unto him, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the  second is like unto it, Thou shalt love thy neighbor as thyself. On these two commandments hang all the law and the prophets.


I'd like to hear the scripture that is used to support this quote of Augustine's.
Firstly, what is "to love God"?
When you love God, probably you won't do things, which can harm him.
To love God really is so big love, that maybe is better to give you another example also.

When you love your kids, you'll try to please them, help them, protect them and so on. Some laws to protect children in your country are totally unnecessary. You need no laws. Because you're trying best as you can. You won't cause bodily injury, you won't let them without food. On the contrary, when your kids are for you just molecules stack, no laws in your country help. You will harm them and they will go to the foster family very soon. 

Another example, when you love you wife (or husband if you're woman), you won't rob her, maltreat her, abase her and so on. You'll give her everything you have, without some knowledge about quote: 


  Love your neighbor as yourself.


These laws become natural for you, without some knowledge about them. Because you can't know everything what Jesus and all the saints said, probably is better just love your God and love your neighbor best as you can, and each law will become natural for you.