Talmud/Seder Moed/Tractate Pesachim/2a
On the light of the fourteenth [of Nissan] we check for leavened foods by candlelight.
Any place which we do not bring leavened foods into does not require checking.
And why did [the sages] say [that we must check up to] two rows in the wine cellar?
[It is] a place which we bring leavened food into.
The House of Shammai say: Two rows upon the entire wine-cellar.
The House of Hillel say: The two outer rows, which are the uppermost.
What is "light"?
Rav Huna said: naghei, and Rav Yehuda said: night.
It might enter your mind that the one who said naghei [means] actual naghei, and the one who said night [means] actual night.
They brought an argument: "The morning was light, and the men were sent off" (Genesis 42:3); it is proven that "light" is day.
Is it written, "The light was morning"? "The morning was light," is written; like one who says, "the morning came light";
and according to Rav Yehuda quoting Rav.
For Rav Yeduda quoted Rav: A person should always enter during ki tov and leave during ki tov.
They brought an argument: "As the light of the morning the sun shall shine" (II Samuel 23:4); it is proven that "light" is day.
Is it written, "Light is morning"? "As the light of the morning," is written.
And this is what it is saying: "As the light of the morning" [begins to shine] in This World,
it shall be like the shining of the sun for the righteous in the World to Come.
They brought an argument: "God called the light, 'day'" (Genesis 1:5); it is proven that "light" is day.
This is what it is saying: To that which lightens and continues to do so, he called "day."
But now, "and to the darkness, he called 'night'." (ibid.) - to that which darkens and continues to do so, he called night?
But we have established that until the stars come out it is day!
Rather, this is what it is saying: The Merciful One called to the light and appointed it over the mandate of the day,
and the Merciful One called to the darkness and appointed it over the mandate of the night.
They brought an argument: "Praise Him, all stars of light" (Psalms 148:3); it is proven that "light" is night.
This is what it is saying: Praise Him, all stars that give light.
But now, is it the stars that give light that are required to praise,
[while] those that do not give light are not required to praise?
But it is written: "Praise Him, all his legions" (ibid. 2).
Rather, this is what it is telling us: That the light of stars is also light.'
For what is there a practical difference? For one who swears off light;
for it was taught: "One who swears off light is forbidden [to enjoy] the light of the stars."
They brought an argument:
"By light the murderer shall arise, he shall kill the poor and the destitute, and at night he shall be like a thief." (Job 24:14);
naghei: "Light." At this point the gemara assumes this to mean "day."
ki tov: "That it was good;" i.e. daytime. Refers to Genesis 1:4, "God saw the light, that it was good." Rav Yehuda quoting Rav thus teaches that a traveler should both depart and arrive while it is light outside.