Why does a bedtime prayer count as part of the redemption blessing?
Rabbi Yochanan (a sage of the Gemara who taught in the Land of Israel in the 200s) said that whoever goes straight from the redemption blessing into the evening Amidah is a "person of the World to Come." The Mi Chamocha page tells that story. But at night Hashkiveinu sits in between. The Gemara's short answer: since the rabbis set it up, it counts as "a long redemption" (Berakhot 4b).
The Gemara does not say why it counts. Later commentators give reasons. Ibn HaYarchi (Rabbi Avraham ben Natan, from Provence, who settled in Spain around 1200), quoted by Abudarham (a commentary on the prayers, Spain, about 1340), points to the words "spread over us." He says "spread" is the language of redemption. In Rut 3:9, Rut asks Boaz, "Spread your wing over your maidservant, for you are a redeemer."
The Raavad (a rabbi of the Middle Ages), quoted in the same place, looks at Egypt. The redemption began at midnight (Shemot 12:29) and went on until morning, so at night it is a long one. He says Hashkiveinu was set up to guard Israel from the satan who destroyed in Egypt. The first card in this prayer shows how the Mishnah Berurah tells that story.
The Gemara explains Rabbi Yochanan's own view this way: redemption is already there at night, but it is complete only at dawn (Berakhot 4b). So the night is the in-between time. A prayer for getting through the hours in between fits there. That last link is ours, not the sources'.
The reasons from Ibn HaYarchi and the Raavad are later explanations. They are two different reasons, and the sources do not set them against each other.
Berakhot 4b,Abudarham, Weekday Prayers, Evening Service,Rut 3:9,Shemot 12:29Who is the "satan" this prayer asks God to remove?
The word satan already came up in the morning prayers. The Yehi Ratzon prayer in the morning blessings explains it: in Hebrew a satan is an opponent, and in the Tanach and the Gemara he acts only inside the limits God sets. Here the question is a different one. Is the satan in Hashkiveinu something outside you, or something inside?
The prophet Zecharyah sees the satan standing at the right hand of Yehoshua the High Priest, "to accuse him" (Zecharyah 3:1). That is an opponent outside a person, making a case against him.
The Gemara's own bedtime prayer points inward too (Berakhot 60b). It uses the same verb as our opening: "that You lay me down in peace." Then it asks: "Let the good impulse rule me and not the evil impulse. Save me from harm. Do not let bad dreams and bad thoughts frighten me." There the dangers of the night are outside you and inside you.
Hashkiveinu itself does not say. It lists dangers from outside (an enemy, plague, sword, famine), then sorrow, then the satan, "from in front of us and from behind us." Abudarham's text of the prayer says "break the satan," not "remove," and he ties the line to Tehillim 91:7, "A thousand may fall at your side," a verse about danger on every side.
Reading the line as a request about both kinds of danger is a reading. The sources leave it open.
Zecharyah 3:1,Berakhot 60b,Abudarham, Weekday Prayers, Evening Service,Tehillim 91:7Why is protection pictured as a shelter and wings, not a wall?
Look at the pictures the prayer uses: a sukkah (a hut of branches) "of Your peace," and "the shadow of Your wings." Neither is a fortress. Yeshayahu 4:6 uses the same picture: "A sukkah for shade by day from the heat, and for refuge and shelter from storm and rain."
Abudarham ties "spread over us" to Tehillim 105:39, which is about the desert: "He spread a cloud as a covering, and fire to light up the night." He ties "the sukkah of Your peace" to Tehillim 91:4, "He covers you with His wing." The Torah says God made Israel live in sukkot when He brought them out of Egypt (Vayikra 23:43). The Gemara records a disagreement about what those were. Rabbi Eliezer says clouds of glory. Rabbi Akiva says real huts (Sukkah 11b).
The last request, "guard our going out and our coming in," is Tehillim 121:8. The Shema tells the Gemara's story of Onkelos and the mezuzah, which is built on this same verse: God guards His people from outside (Avodah Zarah 11a).
On Friday night the same blessing ends differently. In Siddur Sefard, "spread over us the sukkah of Your peace" comes back right before the end, and the closing is about it too: "Blessed are You, Hashem, who spreads the sukkah of peace over us, over all His people Israel, and over Jerusalem." The sukkah, a picture in the middle of the weekday prayer, becomes its last line.
The sources do not say why the prayer chose these pictures over a wall. What they show is where the pictures come from.
Yeshayahu 4:6,Abudarham, Weekday Prayers, Evening Service,Tehillim 105:39, 91:4, 121:8,Vayikra 23:43,Sukkah 11b,Avodah Zarah 11a,Siddur Sefard, Friday night Maariv