Albert Barnes Commentary 1 Kings 18:36

"And it came to pass at the time of the offering of the [evening] oblation, that Elijah the prophet came near, and said, O Jehovah, the God of Abraham, of Isaac, and of Israel, let it be known this day that thou art God in Israel, and that I am thy servant, and that I have done all these things at thy word." — 1 Kings 18:36 (ASV)

At the time of the offering of the evening sacrifice – that is, probably “the ninth hour,” or three o’clock in the afternoon. This would mean about five hours of daylight still remained, during which the other events of the day were accomplished.

Lord God of Abraham, Isaac, and of Israel – This solemn address would call to mind the burning bush at Horeb and the words God spoke there, since this mysterious formula had only been used on that one previous occasion. Its use now was calculated to stir their faith and prepare them to some degree for God’s answering “by fire.”

That I have done all these things at your word – that is, “That I have been divinely directed in all that I have done publicly as a prophet—in proclaiming the drought, in gathering this assembly, and in proposing this trial—and that I have not done these things of my own mind.”