Related על פסחים 4:22

Formerly it was customary to signal with beacons on the high mountain peaks: on the Mount of Olives, on Sartaba, on Agrippina, on the Tabor, on the Hauran and Bet Bilti. R. Shimon ben Elazar says: Also the mountains of Machaerus and Gadara and similar. When do you signal the month? [Answer:] On the night it was switched on. How [one should understand this] ? [Answer:] He fell on a Friday or Sabbath, one signals on Sunday because of it; when the month comes in its time, one signals for it; but if not, one does not signal for his sake. Because of all the months one signaled with signal fires. Said one: Before the sun , so he said nothing. [He said:] To the south of her, his words are valid. If one said: I saw him two ox sticks high, and if one said: three, then the testimony is valid. If one says three, and one says five, they are not taken together; but he is taken together with others [who make the same statement]. Says one I have seen him erect, and one says: I have seen him bent, so they are not taken together, but he is taken together with others [who make the same statement]. If he saw him half in the water, he said nothing; [he saw] him halfway through a cloud, he said nothing. [If he saw] him half through glass, he said nothing. R. Elazar ben R. Zadok says: If he is not seen in his time, the month is not sanctified; because heaven has it already sanctified. And likewise, R. Eleazar ben R. Zadok used to say: The messengers do not go to Syria until they have heard from the mouth of the court: Sanctified.

From what point on the fourteenth [of Nissan] is labor forbidden? Rabbi Eliezer ben Ya'akov says, from the evening (אור) of the fourteenth. Rabbi Yehuda says, from the appearance of the sun. Said Rabbi Eliezer ben Ya'akov, where else do we find that labor is prohibited for only part of the day, and permitted for part of the day? Rabbi Yehuda said to him, it proves itself, since for part [of the day preceding Passover] chametz is forbidden, and for part of it, it is permitted.