You may be thinking of the Scripture which Herbert Armstrong often quoted:

"Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil" (Matthew 5:17).

Yet notice that Christ said he came to "fulfil" the law and the prophets. He was born under the Law (Galatians 4:4) and obeyed the Law perfectly, fulfilling its demands (something none of us could ever do) and He fulfilled all that the prophets prophesied about Him as the Messiah.

The next verse continues:

"For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled" (Matthew 5:18).

Notice how He says, "Till all be fulfilled." Fulfilled means to bring to completion. Christ fulfilled the Law (the entire Old Testament). His words from the cross were:

"It is finished" (John 19:30).

When He said it is "finished" that means our redemption was finished. It is not still being fulfilled. 

"I have finished the work which thou gavest me to do" (John 17:4).

The Jews attempted to keep the Law with its commandments and rules. This led to a spiritual pride. Christ has broken down that barrier (enmity) between Jew and Gentile:

"For he is our peace, who hath made both one, and hath broken down the middle wall of partition between us; Having abolished in his flesh the enmity, even the law of commandments contained in ordinances; for to make in himself of twain [Jews and Gentiles] one new man, so making peace;" (Ephesians 2:14-15)

The definition of biblical grace is "unearned, unmerited favor from God." Works of the Law play no part in qualifying for, maintaining, or receiving our salvation. The works that will follow one's acceptance of Christ as their personal Savior are works of faith that He works in us and through us. To believe there is anything we must do to gain salvation is to confuse the old covenant with the New Covenant and ancient Israel with the New Testament Church. 

 

Not only are we saved by faith rather than by law but law is not to be the rule of life for the believer. We are not to live by law at all. ...Grace supplies the indwelling and filling of the Spirit to enable us to live on a higher plan than law demanded. This all is our portion when we trust Christ as Savior. It is in Christ that we receive everything--salvation and sanctification. ...Let's stop trying some legal system or rote of rules. We have a liberty in Christ. ~ J. Vernon McGee, Vol. 5, Galatians 5:1

Herbert Armstrong tried to interpret the New Testament with the Old. This cannot be done. The Scriptures are a moving revelation; i. e, they move from the knowledge of the Law into the knowledge of grace under the new dispensation. Therefore, one cannot use events recorded in the gospels prior to the death and resurrection of Jesus to try and prove that a Sabbath day is binding on Christians today. The old covenant was beginning to fade after Christ died and rose. Old Covenant points of the Law, such as the Sabbath command, were made invalid and no longer binding on those who were under that earlier covenant. After Jesus rose from the dead and appeared to his disciples he said:

"And he said unto them, These are the words which I spake unto you, while I was yet with you, that all things must be fulfilled, which were written in the law of Moses, and in the prophets, and in the psalms, concerning me" (Luke 24:44). 

Notice the words: "all things must be fulfilled."

The Mosaic Law and all its rituals, days and commandments pointed to Christ who was to come to this earth, be born of a virgin, and die for the sins of the whole world. Those rituals, ordinances and laws from the Old Testament were only shadows of Him. If we have a picture of a loved one, do we continue to hold onto the picture after the person arrives? No, we no longer need the picture, but embrace the reality, which, in this case, is Christ. (Colossians 2:17) [See: Could you explain Colossians 2:16-17? (Q&A)] We no longer need days, laws, rituals, and works of the flesh to please God. We are now accepted in the Beloved (Ephesians 1:6) and all spiritual blessings have been given to us in Christ Jesus. (Ephesians 1:3) God's love in us produces the fruit of the Spirit. This has nothing to do with trying to maintain or qualify for our salvation. To try to apply works of the Law with faith is adding those works to grace, which is impossible. It is an attempt to "earn" grace. Some have called it a "second work of grace." Our love for Him after placing our faith in Him as our Savior has nothing to do with focusing on any part of the Mosaic Law. Mixing faith and works is incompatible when it comes to receiving salvation:

"Now to him that worketh is the reward not reckoned of grace, but of debt. But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness. Even as David also describeth the blessedness of the man, unto whom God imputeth righteousness without works" (Romans 4:4-6).

The book of Acts is often used to try and prove one must keep the Sabbath day. But a search of church history will reveal that the early church met on both days--Saturday and Sunday. The Apostles preached in the synagogues on the Sabbath because that is when the Jews met and it was how the gospel was able to be preached to them. As time went on the church began meeting on Sunday. Some of this is explained in the article: Sabbath and Sunday (Common Misunderstandings). The book of Acts is simply what it says--the acts of the Apostles (or the acts of God through the apostles). It is not a book for finding doctrine. Doctrine is found in the Epistles of Paul. Paul's Epistles to the church make no mention of the need for Christians to keep Sabbath days, or any of the works of the Law, in order to maintain or gain salvation. (Colossians 2:17 is covered above and any good commentary will discuss that verse further.) 

Law-keepers desire to bring others under the bondage of the Law:

"...false brethren unawares brought in, who came in privily to spy out our liberty which we have in Christ Jesus, that they might bring us into bondage" (Galatians 2:4).

Those who believe on Christ and have received Him--by faith--are the sons of God. They do not need to try to qualify for it. 

"But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name" (John 1:12).

"He that hath the Son hath life; and he that hath not the Son of God hath not life. These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life" (1 John 5:12,13).

Notice the above words: "He that hath the son hath life" and "that ye may know that ye have eternal life." Those who believe on the Son (turn to Him and place their faith in Him) hath eternal life. These are the true words of Scripture written after Christ Jesus was raised from the dead.

Strivings after the Law and focusing on it leads to fear, frustration, contention, discouragement, discord and a condemning attitude toward others that are perceived as not keeping the Law. This is a negative goodness. The Law could only bring death (not life) because it demanded absolute perfection. No one is able to live up to that. Christ desires for you to cease from your struggles under the Law and come to understand that there is nothing you can do to receive salvation. We cannot make ourselves holy or acceptable to God by laws, rules or regulations. Read about how H. A. Ironside came to this conclusion after much struggling: Holiness: The True and the False (covers true sanctification; offsite link).

"For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father. The Spirit itself beareth witness with our spirit, that we are the children of God:" (Roman 8:15-16).

Multitudes have been saved down through the centuries by believing in this simple gospel of grace: 

"That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation" (Romans 10:9-10).

When our minds turn to Jesus for salvation, we have freedom from the bondage of the Law. The Spirit of God brings us to Christ, the place of liberty.

Christ fulfilled the following at His first coming:

"The spirit of the Lord GOD is upon me; because the LORD hath anointed me to preach good tidings unto the meek; he hath sent me to bind up the brokenhearted, to proclaim liberty to the captives, and the opening of the prison to them that are bound" (Isaiah 61:1).

After placing our faith and trust in Christ as our Savior and having all our sins washed away, we are now positionally in Him, accepted by God, and all because of what He has already done for us. There is nothing else you can do to earn your salvation. The work of salvation was finished on the cross.