ὥστε μαρτυρεῖτε ἑαυτοῖς ὅτι υἱοί ἐστε τῶν φονευσάντων τοὺς προφήτας.

1. ὥστε
   so that
2. μαρτυρεῖτε
   you testify
   bear witness, testify
3. ἑαυτοῖς
   themselves
   for themselves
4. ὅτι
   that
   because
5. υἱοί
   sons
6. ἐστε
   you are
   are
7. τῶν
   of the
8. φονευσάντων
   having murdered
9. τοὺς
   the
10. προφήτας
    prophets
11.  
    .
     

so that you testify against yourselves that you are sons of those who murdered the prophets.