John Gill Commentary 2 Kings 17:35

"with whom Jehovah had made a covenant, and charged them, saying, Ye shall not fear other gods, nor bow yourselves to them, nor serve them, nor sacrifice to them:" — 2 Kings 17:35 (ASV)

With whom the Lord had made a covenant
As he did at Sinai, (2 Kings 17:15)

and charged them, saying, you shall not fear other gods, nor bow
yourselves to them, nor serve them, nor sacrifice to them ;
all which is contained in the first and second commandments of the law.