What is fulfillment of the law?

Gal 5:¹⁴ For the whole Law is fulfilled in one word, in the statement, “You shall love your neighbor as yourself.”

5:1 ^[a]It was for freedom that Christ set us free; therefore keep standing firm and do not be subject again to a yoke of slavery.

² Behold I, Paul, say to you that if you receive circumcision, Christ will be of no benefit to you. ³ And I testify again to every man who receives circumcision, that he is under obligation to keep the whole Law. ⁴ You have been severed from Christ, you who ^[b]are seeking to be justified by law; you have fallen from grace. ⁵ For we ^[c]through the Spirit, ^[d]by faith, are waiting for the hope of righteousness. ⁶ For in Christ Jesus neither circumcision nor uncircumcision means anything, but faith working through love.

Matt 5:17-20 

Throughout the history of Israel, a pattern is set in play. A promise is given, with qualifications. (Were there qualifications for Abraham?) It was in play when Moses handed the reins over to Joshua, when Joshua took over the promised land, at the end of Joshua's days, and when David died and God promised him that heirs would sit over the kingdom forever IF his descendants followed all the law. 

The model kicks off in Deut 31, when Moses says that Joshua will succeed him. "Be strong and bold is said 3 times.  31:24 When Moses had finished writing down in a book he words of this law to the very end, 25 Moses commanded the Levites who carried the ark of the covenant of the Lord, saying 26 Take this book of the law and put it beside the ark of the covenant of the Lord your God; let it remain there as a witness against you."

In Deut 32, Moses is told that he will die in the sight of the promised land "because both of you broke faith with me among the Israelites at the waters of Meribath-kadesh in the wilderness of Zin, by failing to maintain my holiness among the Israelites. 44: Moses came and recited all the words of this song in the hearing of the people, he and Joshua son of Nun. 45 When Moses had finished reciting all these words to all Israel, 46 he said to them: "Take to heart all the words that I am giving in witness against you today; give them as a command to your children, so that they may diligently observe all the words of the law. 47 This is no trifling matter for you, but rather your very life; through it you may live long in the land that you are crossing over the Jordan to possess."

Deut 34:4 "This is the land of which I swore to Abraham, to Isaac, and to Jacob, saying, I will give it to your descendants'; I have let you see it with your eyes, but you shall not cross over there." 

Earlier stuff Deut 6: Now this is the commandment--the statues and the ordinances--that the Lord your God charge me to teach you to observe in the land that you are about to cross into and occupy, 2 so that you and your children and your children's children may fear the Lord your God all the days of your life, and keep all his decrees and his commandments that I am commanding you, so that your days may be long. 3 Hear therefore, O Isreael, and observe the diligently, so that it may go well with you, and so that you may multiply greatly in a land flowing with mild and honey, as the Lord the God of your ancestors, has promised you." Deut 29:9Therefore diligently observe the words of this covenant in order that you may succeed in everything that you do.

Similar references Deut: 4:29, 6:2, 8:6, 9:5, 11:1. Deut 17:18 When he has taken the throne of his kingdom, he shall have a copy of this law written for him int he presence of the Levitical priests. 19 It shall remain with him and he shall read in it all the days of his life, so that he may learn to fear the Lord his God, diligently observing all the words of this law and these statues... so that he and his descendants may reign long over his kingdom in Israel.

Ps 132:11

¹¹ The Lord swore to David a sure oath
    from which he will not turn back:
“One of the sons of your body^[a]
    I will set on your throne.
¹² If your sons keep my covenant
    and my testimonies that I shall teach them,
their sons also forever
    shall sit on your throne.”

This is repeated throughout the chapter and subsequent chapters. The promise is connected to the complete fulfillment of the law.

Joshua 1:6 Be strong and courageous, for you shall put this people in possession of the land that I swore to their ancestors to give the. Only be strong and very courageous, being careful to act in accordance with all the law that my servant Moses commanded you do not turn from it to the right hand or to the left, so that you may be successful wherever yo go. This book of the law shall not depart out of your mouth; you shall meditate on it day an night so that you may be careful to act in accordance with all that is written in it. For then you shall make your way prosperous, and then you shall be successful. I hereby command you: be strong and courageous; do no be frighted or dismayed, for the Lord your God is with you wherever you go.  

In Joshua 23, Joshua is old. V6 Therefore be very steadfast to observe and do all that is written in the book of the law of Moses, turning aside from it neither to the right nor to the left, 7 so that you may not be mixed... Check out chapter 23 as well. 23:25 So Joshua made a covenant with the people that day, and made statutes and ordinances for them at Shechem. 26 Joshua wrote these words in the book of the law of God; and he took a large stone, and set it up there under the oak in the sanctuary of the Lord. 27 Joshua said to all the people, "See this stone shall be a witness against us; for it has heard all the words of the Lord that he spoke to us; therefore it shall be a witness against you, if you deal falsely with your God." 

In 1 Kings 2, David grows old and instructs Solomon. 2 Be strong, be courageous, 3 and keep the charge of the Lord your God, walking in his ways and keeping his statues, his commandments, his ordinances, and his testimonies, as it is written in the law of Moses, so that you may prosper in all that you do and wherever you turn. 4 Then the Lord will establish his word that he spoke concerning me: "if your heirs take heed to their way, to walk before me in faithfulness with all their heart and with all their soul, there shall not fail you a successor on the throne of Israel."

2 Sam 7 is God talking to David about building him a house, however does not list a condition of obedience. This seems to be in isolation compared with the rest.

(Are there more examples?)

Jesus turned that model on its ear. He said that HE had come to fulfill it. Prior to that, WE were asked to fulfill it. Now He was there. And the price exacted for inheriting the kingdom, the land, eternal reward was faith and love.