Philippians 3:2

Textus Receptus:
βλεπετε τους κυνας βλεπετε τους κακους εργατας βλεπετε την κατατομην

King James:
Beware of dogs, beware of evil workers, beware of the concision.

Comments:
beware...beware...beware: Although Christians are to live beyond fear (1 John 4:18) they are not to be imprudent. This balance makes it clear that Jesus' command to the seventy in Matthew 10:16 (to be "wise as serpents, but harmless as doves") also applies to contemporary believers.

dogs...evil workers...concision: Paul is referring to the same people three different ways, with a slightly different emphasis each time. That they are dogs warns believers that they are unclean and outsiders (non-believers). John uses the word this way in Revelation 22:15; Jesus in Matthew 7:6. That they are evil workers points to the injurious nature of their activity. It is not just rational or the best doctrine to avoid their heresies, but actually important for the welfare of the Philippians. Matthew 21:41 uses the word for "evil" to modify destruction. Paul makes a change with the word concision. It is singular, pointing to the dogs and evil workers as a single group. Although heretics may not agree with each other, they are united by the fact that they stand against and threaten the word and work of God.

Expanded Paraphrase:
Be aware of and look out for those unclean, attacking dogs. Be aware of and look out for those whose work results in your own destruction. Be aware of and look out for those who in all their different ways cut brutally through the truth (ignoring and destroying it), rather than cleanly around it.