We take special heed of someone's last words. Last words usually mean a lot to the person leaving. Before Jesus ascended to heaven He left these words:
Matthew 28:18-20 KJV
And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth. Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the end of the world. Amen.
Jesus specifically instructed those who were there to teach others to observe all things He had commanded them. That was important to Him. Today, we have people teaching that Jesus' instructions are not all relevant because those were teaching before Jesus died on the cross. After He died those instructions are no longer applicable. This teaching does not seem to coincide with Jesus' last words. "All things I have commanded you" includes the things He taught before His death and resurrection. Jesus then promised that He will be with those who do so.
May we learn to practice and teach what Christ Jesus had instructed throughout His life. His life has impacted people for thousands of years until today.