'Be on Your Guard' in the Bible

"Let everyone be on your guard against his neighbor, and you must not trust in any brother, for everyone surely betrays, and every neighbor goes about [with] slander.

Thus says Yahweh, "Be on your guard for the sake of yourselves, that you must not carry a burden on the day of the Sabbath, and you must [not] bring [it] through the gates of Jerusalem.