Ambrose of Milan

Great is the virtue of fasting. Indeed, its military appearance is so beautiful that it delightfully attracts and elevates humans to heaven for fasting and for Christ: so powerful that it raises men up to heaven. And to use more human than divine examples, from the fasting mouth of Elijah a voice was uttered that closed heaven to the sacrilegious people of the Jews. For when Ahab, the king, had set up an altar to the idol, according to the words of the prophet, there was no rain for three years and six months upon the earth. …

On Elijah and Fasting, Chapter 2, 2-3 ↗