12-13 And now, Israel, what does the Lord your God require of you? He requires only that you fear the Lord your God, and live in a way that pleases him, and love him and serve him with all your heart and soul. And you must always obey the Lord’s commands and decrees that I am giving you today for your own good. 14-15 Look, the highest heavens and the earth and everything in it all belong to the Lord your God. Yet the Lord chose your ancestors as the objects of his love. And he chose you, their descendants, above all other nations, as is evident today.

16-19 Therefore, change your hearts, and stop being stubborn. For the Lord your God is the God of gods and Lord of lords. He is the great God, the mighty and awesome God, who shows no partiality and cannot be bribed. He ensures that orphans and widows receive justice. He shows love to the foreigners living among you and gives them food and clothing. So you, too, must show love to foreigners, for you yourselves were once foreigners in the land of Egypt. 

20-22 You must fear the Lord your God and worship him and cling to him. Your oaths must be in his name alone. He alone is your God, the only one who is worthy of your praise, the one who has done these mighty miracles that you have seen with your own eyes. When your ancestors went down into Egypt, there were only seventy of them. But now the Lord your God has made you as numerous as the stars in the sky! Deuteronomy 10:12-22 New Living Translation. (English Standard Version link)

Imagine if a family of young children were orphaned through a terrible tragedy, but a kind and wealthy gentleman and his wife who’d been good friends with their parents took them into their home to foster them. As the children grew older the man asked if they would like to be adopted as his own children and take his surname as their own. Would it not be sad if the children said yes, and took his name – but went on to behave in such ways that the family name's reputation was ruined? Moses raises the possibility of a similar situation for Israel. What did he tell them about their relationship with God in vs 14-15?

The God to whom all heaven and earth belonged had chosen them to belong to His family. It was an act of love based on the love God had for their ancestors – i.e. Abraham and Isaac and Jacob. But what did God expect and hope for in return? (vs 12-13)

Moses urged them to give God the deep respect and love that He so well deserves. He urged them to put aside the stubbornness they had showed up to that point, and to begin to care for others as God had cared for them. He reminded them that their love wasn't to be a clique, but they were to show love and fairness even towards foreigners who may live among them too. In a similar way, centuries later, Jesus Christ said to his disciples. “I am giving you a new commandment - that you love one another. Just as I have loved you, so you must love one another. Your love for one another will prove to the world that you are my disciples.” (John 13:34)

What was the other requirement Moses pointed out in vs 20-22 that they needed to do?

They were to remain faithful and loyal to God. They were not to take the names of other gods in any oaths they made. What is the reason Moses gives in those verses why they were to cling to the God of Abraham, Isaac and Jacob?

It was God who had changed them from being a small wandering nomadic tribe into a mighty nation. He had made them His family. So the right thing to do would be to want to uphold the reputation of God's name. And the way to do that would be by obeying the good commandments He had given them. Christians are called to do the same. Jesus said: “If you love me, you will keep my commands. And I will ask the Father, and he will give you another Counsellor to be with you forever.” (John 14:15) That counsellor is the Holy Spirit who God gives to those who turn from sin and stubbornness and believe on His Son for forgiveness. It is the Spirit who works in us so that our lives grow in ways that bring honour to God's name.