Joel 3:1

For, behold -The prophet by the word, “for,” shows that he is about to explain in detail, what he had before spoken of, in sum. By the word, “behold,” he stirs up our minds for something great, which he is to set before our eyes, and which we should not be prepared to expect or believe, unless he solemnly told us, “Behold.” As the detail, then, of what goes before, the prophecy contains all times of future judgment on those who should oppose God, oppress His Church and people, and sin against Him in them and all times of His blessing upon His own people, until the Last Day.