(Rebbi): (R. Eliezer says that the Mitzvah is until the end of the first Mishmar.) There are four Mishmaros during the day, and four Mishmaros at night (each is three hours);

An Oneh is one part in 24 of an hour. An Es is one part in 24 of an Oneh. A Rega is one part in 24 of an Es.

Question: How long is a Rega?

Note: A simple calculation shows that it is one part in 13,284 of an hour (about a quarter of a second)! Perhaps we ask what is the significance of a Rega. Perhaps the answer alludes to how Bil'am could have cursed Yisrael in the Rega of Hash-m's anger. Alternatively, we ask because others give different Shi'urim. (PF)

Answer #1 (R. BeraChiya citing R. Chelbo): It is long enough to say it (the word 'Rega.')

Answer #2 (Rabanan): It is the time of an eye's blink.

Answer #3 (Shmuel - Beraisa): Rega is one part in 56,848 of an hour (about one part in 16 of a second).

(R. Nasan): [There are] three [Mishmaros at night. We learn from] "Rosh ha'Ashmores ha'Tichonah" (there is one before and one after).

(R. Zerikan and R. Ami citing Reish Lakish): Rebbi learns from "Chatzos Laylah Akum Lehodos Lecha Al Mishpetei Tzidkecha", and it says "Kidmu Einai ha'Ashmuros" (there are two Ashmuros after midnight).

R. Chizkiyah citing R. Zerikan and R. Ba - one of them gave Rebbi's reason, and one of them gave R. Nasan's reason.

The one who gave Rebbi's reason - it is "Chatzos Laylah..." The one who gave R. Nasan's reason - it is "Rosh ha'Ashmores ha'Tichonah."

Question: How does R. Nasan expound Rebbi's reason (verse), "Chatzos Laylah..."?

Answer: Sometimes [David rose] at midnight (one and a half Mishmaros before morning), and sometimes his eyes woke [two full] Mishmaros [eight hours before morning].

How is this? When David ate a royal meal [for supper, he did not rise until] Chatzos Laylah. When he ate by himself, "Kidmu Einai ha'Ashmuros."

In any case, morning never came and found David sleeping. This is what David said "Urah Kevodi Urah ha'Nevel v'Chinor A'irah Shachar" - let my honor be [Batel, and I will be] woken due to the honor of my Creator. My honor has no significance in front of the honor of my Creator.

"A'irah Shachar" - I would wake [before] the morning. The morning would not wake me!

His Yetzer ha'Ra instigated, and told him "David - the way of kings is that the morning wakes them, and you said "A'irah Shachar"?!

The way of kings is to sleep until three hours [of the day], and you said "Chatzos Laylah Akum"?!

And [David] said [back, I rise early to investigate] "Al Mishpetei Tzidkecha" (so I will be able to rule properly - MAHARA FULDA).

Question: What did David do [when he woke]?

Answer (R. Pinchas citing R. Elazar b'Ribi Menachem): He took a lyre and harp, and put them at the head of his bed. He rose at midnight and played on them, in order that Chaverei Torah (Chachamim) will hear;

What would Chaverei Torah say? If David ha'Melech engages in Torah, all the more so we [will]!

(Levi): A harp hung near David's window, and the north wind would blow on it at night and wave it, and it would play by itself.

Source: "V'Hayah k'Nagen ha'Menagen" - it does not say 'k'Nagen b'Menagen' (he played on the instrument), rather, "k'Nagen ha'Menagen" - the harp played by itself. (Hagahas HA'GRA - even though the verse discusses Elisha, we learn from it that a harp can play by itself.)

Question: How does Rebbi expound [the verse] of R. Nasan, "Rosh ha'Ashmores ha'Tichonah"?

Answer #1 (Rav Huna): [It was at] the end of the second [Mishmar], and the start of the third - they comprise the middle (Tichon) of the night.

Objection (R. Mana): Is it written Tichonos?! Is it not [written] 'Tichonah' (singular)?!

Answer #2: The first [Mishmar] does not count, for people are awake until then. (David rose in the middle of the three Mishmaros during which people sleep.)