That's EXACTLY what it says in the Peshitta. Read if for yourself.
Hebrews 4:9 It is therefore the duty of the people of God to keep the Sabbath.
no, that's what the well-known Judaizing false teacher George Lamsa wrote.
read the actual Peshitta:

the word "duty" is not present.
the words "to keep" is not present.
you should fear God, and stop thinking to add to His word.