Complex sentence: Hostages had been seen earlier holding up a black Islamic flag with the Muslim "shahādah" in Arabic, saying, "There is no God but Allah and Muhammad is the messenger of God".
Split into simpler sentences: Hostages had been seen earlier holding up a black Islamic flag with the Muslim "shahādah" in Arabic. Hostages were seen holding up a jihadist black flag with the Arabic "shahādah" "There is no God but Allah and Muhammad is the messenger of God".