Deuteronomy 6:25 English Standard Version (ESV) And it will be righteousness for us, if we are careful to do all this commandment before the Lord our God, as he has commanded us.’
This will be our righteousness, if we do the commands. This is the Old Testament standard requirement for righteousness. Here is the command.
Deuteronomy 6:4-9 English Standard Version (ESV)
4 “Hear, O Israel: The Lord our God, the Lord is one. 5 You shall love the Lord your God with all your heart and with all your soul and with all your might. 6 And these words that I command you today shall be on your heart. 7 You shall teach them diligently to your children, and shall talk of them when you sit in your house, and when you walk by the way, and when you lie down, and when you rise. 8 You shall bind them as a sign on your hand, and they shall be as frontlets between your eyes. 9 You shall write them on the doorposts of your house and on your gates.
Try as they might, they failed and they had no righteousness of their own.
Romans 3:9-11 English Standard Version (ESV)
No One Is Righteous
9 What then? Are we Jewsany better off? No, not at all. For we have already charged that all, both Jews and Greeks, are under sin, 10 as it is written: 11 “None is righteous, no, not one; no one understands; no one seeks for God.”
The failings of the followers was in their ability to love with all heart, all soul and all strength. There was no inner strength within them capable of giving all. Self-interest remained an issue because the heart had not changed.
Ezekiel 11:19 English Standard Version (ESV) And I will give them one heart, and a new spirit I will put within them. I will remove the heart of stone from their flesh and give them a heart of flesh,
Ezekiel 36:26 English Standard Version (ESV) And I will give you a new heart, and a new spirit I will put within you. And I will remove the heart of stone from your flesh and give you a heart of flesh.
It was so important that Ezekiel repeated it twice with one exception, this new heart was one heart.