Mekilta, Tractate Shabbat
We read in the Torah, 'Truly you should keep my Sabbaths, for it is a sign between me and you throughout your generations, that you may know that I am the Lord who sanctifies you.' (Exodus 31:12-13). This reflects the future world, which is characterized by a kind of holiness possessed by the Sabbath of this world. We learn that the Sabbath possesses a holiness like that of the future world. And therefore it says: 'A Psalm; a song of the Sabbath day,' referring to the world in which there is Sabbath all the time.'
Midrash Tanhuma, Parashat Vayera
Why does a person not pray ‘Blessed are You, Adonai, Healer of the people Israel’ [one of the 13 weekday petitionary blessings] on Shabbat? Lest they remember a sick loved one and then become sad on the holy Shabbat which has been set aside as a day of rest and delight. Therefore, on Shabbat we consciously choose to enjoy and celebrate the unique sanctity of the day.
Talmud, Tractate Shabbat 54b:
It was related that Rav, and Rabbi Ḥanina, and Rabbi Yoḥanan, and Rav Ḥaviva taught the statement cited below. ... they said: Anyone who had the capability to effectively protest the sinful conduct of the members of his household and did not protest, he himself is apprehended for the sins of the members of his household and punished. If he is in a position to protest the sinful conduct of the people of his town, and he fails to do so, he is apprehended for the sins of the people of his town. If he is in a position to protest the sinful conduct of the whole world, and he fails to do so, he is apprehended for the sins of the whole world.
(ז) עַל אֵלּוּ מַתְרִיעִין בְּשַׁבָּת, עַל עִיר שֶׁהִקִּיפוּהָ גוֹיִם אוֹ נָהָר, וְעַל הַסְּפִינָה הַמִּטָּרֶפֶת בַּיָּם. רַבִּי יוֹסֵי אוֹמֵר, לְעֶזְרָה וְלֹא לִצְעָקָה. שִׁמְעוֹן הַתִּמְנִי אוֹמֵר, אַף עַל הַדֶּבֶר, וְלֹא הוֹדוּ לוֹ חֲכָמִים:
(7) For the following calamities an alarm is to be sounded even on the Sabbath:—For a city surrounded by enemies; for a flood threatening to inundate the country; for a ship in imminent danger of being wrecked at sea [in a storm]. R. José says, This sounding is to obtain assistance [from people], not as an imploring cry [to God]." Simeon the Temanite says, "They shall also sound on the Sabbath in case of pestilence;" but the sages did not agree with him [in this].
אלא בשופרות דכולי עלמא לא פליגי דקרי לה התרעה כי פליגי בעננו מר סבר קרי לה התרעה ומר סבר לא קרי לה התרעה למ"ד בעננו כל שכן בשופרות ולמ"ד בשופרות אבל בעננו לא והתניא ושאר כל מיני פורעניות המתרגשות כגון חיכוך חגב זבוב וצירעה ויתושין ושילוח נחשים ועקרבים לא היו מתריעין אלא צועקין מדצעקה בפה התרעה בשופרות תנאי היא דתניא על אלו מתריעין בשבת על עיר שהקיפוה גייס או נהר ועל ספינה המטורפת בים ר' יוסי אמר לעזרה אבל לא לצעקה במאי אילימא בשופרות שופרות בשבת מי שרי אלא לאו בעננו וקרי לה התרעה ש"מ:
The Gemara asks: With what do they sound the alarm? Rav Yehuda said: With shofarot. And Rav Yehuda, son of Rav Shmuel bar Sheilat, said in the name of Rav: With the Aneinu prayer.
This is a dispute between tanna’im (early rabbis), as we learned in a mishna: For the following calamities they sound the alarm even on Shabbat: For a city that is surrounded by an enemy army or in danger of being flooded by a river, or for a ship tossed about at sea. Rabbi Yosei said: An alarm may be sounded on Shabbat to summon help, but it may not be sounded for crying out to God.
The Gemara clarifies this case. With what do they sound the alarm? If we say with shofarot, is the sounding of shofarot permitted on Shabbat? Even when Rosh HaShana occurs on Shabbat, one must refrain from sounding the shofar on that day. Rather, is it not the case that this is referring to the recitation of the Aneinu prayer, and yet the mishna calls this recitation: Sounding the alarm. Conclude from this that there is a rabbi who maintains that sounding of the alarm is in fact performed by prayer, as claimed by Rav Yehuda, son of Rav Shmuel bar Sheilat.
Susannah Heschel, "Following in my father's footsteps: Selma 40 years later"
https://www.dartmouth.edu/~vox/0405/0404/heschel.html
For my father, though, the march was not simply a political demonstration, but a religious occasion. He saw it as a revival of prophetic Judaism's political activism and also of the traditions of Hasidism, a Jewish pietistic revival movement that arose in the late eighteenth century, according to which walking could be a spiritual experience.
He said it reminded him of the message of the prophets, whose primary concern was social injustice, and of his Hasidic forebears, for whom compassion for the suffering of other people defined a religious person...
When he came home from Selma in 1965, my father wrote, "For many of us the march from Selma to Montgomery was about protest and prayer. Legs are not lips and walking is not kneeling. And yet our legs uttered songs. Even without words, our march was worship. I felt my legs were praying."