בֶּן־אָדָ֕ם שִׂ֥ים פָּנֶ֖יךָ אֶל־הָרֵ֣י יִשְׂרָאֵ֑ל וְהִנָּבֵ֖א אֲלֵיהֶֽם׃
’Son of man, set thy face toward the mountains of Israel, and prophesy against them,
Mishnah Rosh Hashanah
Originally they used to light torches [to signal that the new month had been decreed]. When the Samaritans disrupted this, they decreed that messengers should go out.