The words spoken by Jesus, being the Word of God, are true in Matthew 5:17-20! Here they are:
17 "Do not think that I came to abolish the Law or the Prophets; I did not come to abolish but to fulfill.
18 "For truly I say to you, until heaven and earth pass away, not the smallest letter or stroke shall pass from the Law until all is accomplished.
19 "Whoever then annuls one of the least of these commandments, and teaches others [to do] the same, shall be called least in the kingdom of heaven; but whoever keeps and teaches [them], he shall be called great in the kingdom of heaven.
20 "For I say to you that unless your righteousness surpasses [that] of the scribes and Pharisees, you will not enter the kingdom of heaven.
Jesus fulfilled the Law including the 10 commandments. Jesus said that "not the smallest letter or stroke shall pass from the Law until all is accomplished." This is the same Jesus that while on the cross said:
"It is finished!" (John 19:30)
Therefore, Jesus accomplished all including satisfying (a synonym for fulfill in Matthew 5:17) the Law including the 10 commandments.
And, about Matthew 5:20, Lord Jesus is the righteous One, and we beleivers inherit His righteousness (2 Corinthians 5:21), so we believers are more righteous than the scribes and Pharisees because of the Lord Jesus! It is not what we beleivers do, rather it is the Lord Jesus.
God's Word in the
"Exclusively Scripture With Bible Citations Post" (in this thread) clearly shows God's Word explaining believers covered by the Blood of Jesus of the New Covenant are not bound to the Old Covenant which includes the 10 commandments for the Lord Jesus said that He satisfies the Law which includes the 10 commandments. The Lord Jesus satisfies the Law which includes the 10 commandments (Matthew 5:17); furthermore, the Lord Jesus established "the New Covenant" (Luke 22:20) and that when He said, "A new [covenant]," He has made the first obsolete (Hebrews 8:13).
LISTEN TO GOD'S WORD:
"Do not think that I came to abolish the Law or the Prophets; I did not come to abolish but to satisfy." (Matthew 5:17)
"For the Law, since it has [only] a shadow of the good things to come [and] not the very form of things" (Hebrews 10:1)
"And in the same way [He took] the cup after they had eaten, saying, 'This cup which is poured out for you is the new covenant in My blood.'" (Luke 22:20)
"When He said, 'A new [covenant],' He has made the first obsolete." (Hebrews 8:13)