The work shall fulfill till the end of the world. Does this world has PASSED away? Look at verse 20. Did Jesus says to them till I die on the cross? Don't stop at Matthew 15:17. You must read Matthew 5:17-20. And focused on verse 18.
Jesus does have HIGH standards for his followers. It is the Jewish religious leaders who wrongly view Jesus as transgressing the Law.
This is why they conspire to kill Jesus.
At Matthew 5:17 Jesus tells them he came Not to destroy the Law but to fulfill the Law, and Jesus urged others to have the same regard - Matthew 5:19.
At Matthew 5:18 is Not about a literal Heaven and Earth passing away but Jesus was using what is called an hyperbole.
So, what Jesus was saying was equivalent to meaning ' never '. Never happen that Heaven and Earth be destroyed.- Ecclesiastes 1:4 B.
Thus, God's Word would be fulfilled through Jesus down to the smallest detail. - Isaiah 40:8
This is why Luke could write at Luke 16:17 that it would be easier for Heaven and Earth to pass away than for a letter of the Law to go unfulfilled.
Unless Jesus' followers would surpass the ' righteousness ' of the Pharisees they would Not enter into the kingdom of heaven - Matthew 5:20
Jesus pronounced MANY ' woes ' against those hypocritical Pharisees in the 23rd chapter of Matthew.- Matthew 15:7-9.
What work shall be fulfiied to the 'end of the world' ( this unrighteous system of things ) would be the international work of Matthew 24:14; Acts 1:8.
This is because God accepted Jesus' ransom sacrifice - Hebrews 9:24 - and why Romans 10:4 informs us that Jesus fulfilled the Law.
The Constitution of the Mosaic Law was only for one nation the nation of ancient Israel and could declare No one as righteous - Galatians 2:16
The 'Law of Christ' (Galatians 6:2 ) is for all peoples who want to be declared as righteous ones.
Any thoughts about Romans 3:20___________________