Melachim Bais 23:3

And HaMelech stood by HaAmmud, and cut HaBrit before HASHEM, to walk after HASHEM, and to be shomer mitzvot over His commandments and His edot and His chukkot with all their lev and all their nefesh, to carry out these Divrei HaBrit that were written in this Sefer. And kol HaAm stood [under oath] to HaBrit.