וַיְהִי֙ יָמִ֣ים רַבִּ֔ים וּדְבַר־יְהוָ֗ה הָיָה֙ אֶל־אֵ֣לִיָּ֔הוּ בַּשָּׁנָ֥ה הַשְּׁלִישִׁ֖ית לֵאמֹ֑ר לֵ֚ךְ הֵרָאֵ֣ה אֶל־אַחְאָ֔ב וְאֶתְּנָ֥ה מָטָ֖ר עַל־פְּנֵ֥י הָאֲדָמָֽה׃
And it came to pass after many days, that the word of the LORD came to Elijah, in the third year, saying: ‘Go, show thyself unto Ahab, and I will send rain upon the land.’
Read halakhic rulings (Jewish law) on I Kings 18:1: and classical halakhic sources.