Yes, starting in Deut 6:4 and following plus a portion of Numbers. It was part of a prayer that was prayed twice a day, once in the morning and once in the evening. It was known as the Shema.
To fulfill a commandment was not only to understand the commandment mentally, but to live the commandment out as well (strength) as God had intended. You see, in the passage you site above, there are three parts in which we "love the Lord."
BTW, it would read, deut 6:5
all your heart, soul and strength.
1. heart. What does it look like to love God with your heart? To answer this, one would need to know the Hebrew understanding of what the function of the heart was. In this case, it functioned as the mind as in intellectual thought, not purely emotion for emotion was seated in the bowels, not the heart.
2. Soul, what does it look like to love God with all your soul? To answer this, one would have to understand how a Hebrew viewed the soul in it's different layers and fuctions.
3. Strength, what does it look like to love God with all your strength? To answer this, one would have to understand how a Hebrew understood his strength. This is by far the easiest as it pertained to the work of ones hand, which is attributed and tied to ones heart and soul.
When one is living their life in accordance with this commandment, it would be said that they have fulfilled the commandment.
This is what Paul is speaking about when he speaks on the fulfillment of the law as loving ones neighbor as yourself and if you understand this commandment, then you also understand that sometimes loving your neighbor means doing more for your neigbor than you may do for yourself.
You see, while we were still sinners, Christ died for us and by doing so, shed his blood to atone for our sins. Truly, Christ fits the bill for fulfilling the commandment of loving ones neighbor. Do you agree?
Now then, when it comes to where Jesus quotes the law, and pulls out the two greatest commandments for which all of the 613 commandments hinge upon, it is based on not only the shema, but is also seen directly within the 10 commandments and if you notice, the first 5 commandments are related to how we interact with God, and the last five are related to how we interact with each other. However, if you notice, the 5th commandment speaks on honoring ones parents to which you may ask, "How is that related to honoring God". And it is certainly something I would have you ponder
So you see, Jesus not only shows the greatest commandment, but he also rightly points out the second greatest commandment. It is our job once we know these commandments to live them out and thus, fulfill the commandments. There is a difference ya know, and Paul, in Galatians is speaking of the one who fulfilled the commandment to love their neighbor as themself as only Jesus could do.