Mosiah 17:20

And now when Abinadi had said these words, he fell, having suffered death by fire; yea, having been put to death because he would not deny the commandments of God: having sealed the truth of his words by his death.

After Abinadi said these words, he fell down. He had died by fire. He was killed because he would not deny God’s commandments. He proved his words were true by dying for them.

With those words, Abinadi collapsed and died in the flames. He was executed because he refused to deny God’s commands. He sealed the truth of his message with his life.