Jezekiel 20:12

12 And I gave them my sabbaths, that they should be for a sign between me and them, that they should know that I am the Lord that sanctify them.

Jezekiel 20:12 In-Context

10 And I brought them into the wilderness.
11 And I gave them my commandments, and made known to them mine ordinances, all which a man shall do, he shall even live in them.
12 And I gave them my sabbaths, that they should be for a sign between me and them, that they should know that I am the Lord that sanctify them.
13 And I said to the house of Israel in the wilderness, Walk ye in my commandments: but they walked not , and they rejected mine ordinances, which a man shall do, he shall even live in them; and they grievously profaned my sabbaths: and I said that I would pour out my wrath upon them in the wilderness, to consume them.
14 But I wrought that my name should not be at all profaned before the Gentiles, before whose eyes I brought them out.

The Brenton translation of the Septuagint is in the public domain.