NET
4 Now this matter arose because of the false brothers with false pretenses who slipped in unnoticed to spy on our freedom that we have in Christ Jesus, to make us slaves.
Darby
4 and [it was] on account of the false brethren brought in surreptitiously, who came in surreptitiously to spy out our liberty which we have in Christ Jesus, that they might bring us into bondage;
KJV
4 And that because of false brethren unawares brought in, who came in privily to spy out our liberty which we have in Christ Jesus, that they might bring us into bondage: