1 Kings 18:14

And now thou sayest, Go, tell thy lord, Behold, Elijah is here: and he shall slay me.

When Obadiah speaks these words he is telling Elijah that to go and announce to Ahab that Elijah is here will cause Ahab to kill him. He expects that the Spirit of the Lord may carry Elijah away before Ahab can find him, so that the announcement will prove empty. His fear is sharpened because Ahab has searched throughout the kingdoms for Elijah, and Obadiah believes Ahab will hold him responsible and take his life if the prophet cannot then be found.

This happens amid severe persecution in which Jezebel is killing the prophets of the Lord. Despite that danger Obadiah has remained faithful to God, hiding a hundred of the Lord's prophets and feeding them and protecting them. Even while fearing what Ahab will do to him, Obadiah declares that he has feared the Lord from his youth.

He pleads with Elijah not to put him in this danger of death by sending him with the message. Elijah answers by assuring him, even with an oath, that he will surely show himself to Ahab that same day and meet him. Elijah then sends the message through Obadiah rather than going to the king himself, so that Ahab must come to Elijah.

The verse belongs to Elijah's work against Israel's idolatry, which included his stand on Mount Carmel and the rain that followed. That faithful warning and public witness came before Elijah later weakened under Jezebel's threats after the victory God had given him on Carmel and fled into the wilderness in fear. That flight is presented as a failure of faith that cut short the work he had begun, leading God to direct him to appoint another prophet in his place. Yet God did not abandon Elijah, but took him into God's presence rather than letting him die in the wilderness.