Our verses. This means: they are nearly ready to kill their prophets. "Say: Shall I inform you of something worse than that?" meaning, worse than their killing of their prophets. "The Fire." It is worse than what they did to their prophets; that is, worse than their killing of them.
Muhammad said: Whoever reads "The Fire" (an-nār) in the nominative case (marfūʿ), it is on the meaning: "It is the Fire."
Surah al-Hajj from verse 73 to verse 76.