Brethren, be followers together of me, and mark them which walk so as ye have us for an ensample.
Note 1 at Php 3:17: The Greek word that was translated "mark" in this verse is "SKOPEO," and it literally means "to take aim at (spy)" (Strong's Concordance). Paul was telling the Philippians to separate themselves from the people who were not living according to the example Paul had set.
Note 2 at Php 3:17: Paul called upon the Philippians to imitate his own example and not that of the Judaizers or self-indulgent Christians (Php 3:18-19). An "ensample" is one who serves as a pattern, model, illustration, or sample.
Paul had suffered the loss of all things for Christ (Php 3:7), accounted all things dung in comparison to knowing Christ (Php 3:8), shared in the fellowship of Christ's sufferings (Php 3:10), forsaken his own righteousness and accepted Christ's alone (Php 3:9), forgotten those things that were behind and reached toward the prize that was heavenward in Christ Jesus (Php 3:13-14), and was walking according to the light and understanding of God's Word that he had (Php 3:15-16). Here, he was admonishing other Christians to follow that example (1Co 11:1, 1Ti 4:12, and 1Pe 5:1-3).