Source Sheet based on a compilation by Rabbi Scott Bolton on www.sefaria.org
(1) When the people saw that Moses was so long in coming down from the mountain, the people gathered against Aaron and said to him, “Come, make us a god who shall go before us, for that man Moses, who brought us from the land of Egypt—we do not know what has happened to him.”
Rashi on Exodus 32:1
(1) כי בשש משה [AND WHEN THE PEOPLE SAW] THAT MOSES DELAYED LONG — ...On the sixteenth of Tammuz Satan came and threw the world into confusion, giving it the appearance of darkness, gloom and disorder that people should say: “Surely Moses is dead, and that is why confusion has come into the world!” He said to them, “Yes, Moses is dead, for six hours (noon) has already come (בשש = בא שש) and he has not returned etc.” — Shabbat 89a (cf. Rashi and Tosafot there and Tosafot on Bava Kamma 82a ד"ה כדי).
(25) If there is anxiety in a man’s mind let him quash it, And turn it into joy with a good word.
The Gemara explains another verse in Proverbs: “If there is care in a man’s heart, let him quash it [yashḥena]” (Proverbs 12:25). Rabbi Ami and Rabbi Asi dispute the verse’s meaning. One said: He should forcefully push it [yasḥena] out of his mind. One who worries should banish his concerns from his thoughts. And one said: It means he should tell [yesiḥena] others his concerns, which will lower his anxiety.
The Gemara quotes additional statements from the book of Ben Sira: Do not suffer from tomorrow’s trouble, that is, do not worry about problems that might arise in the future, as you do not know what a day will bring. Perhaps when tomorrow comes, the individual who was so worried will not be among the living, and he was consequently upset over a world that is not his. Prevent a crowd from inside your house, do not let many people enter, and do not even bring all your friends into your house. Make sure, however, that a crowd seeks your welfare, and that you have many allies.
§ It is written in one verse: “Doeg the Edomite” (I Samuel 22:9), and it is written in another verse: “And the king said to Doyeig” (I Samuel 22:18). Rabbi Yoḥanan says in explaining the discrepancy: Initially, the Holy One, Blessed be He, sat and was concerned [doeg] that perhaps this person would emerge to undertake an evil path. After he emerged on that path, God said: Alas [vai], that person has emerged to undertake an evil path.
Implication- the value of anxiety can be found in its ability to prepare you for the eventual "Vaay", the actual negative thing you were worried about. Worry allows you to minimize the discrepancy between before and after the traumatic, anxiety inducing event.
The LORD spoke to Moses, saying: Instruct the Israelites to remove from camp anyone with an eruption or a discharge and anyone defiled by a corpse. Remove male and female alike; put them outside the camp so that they do not defile the camp of those in whose midst I dwell. The Israelites did so, putting them outside the camp; as the LORD had spoken to Moses, so the Israelites did.
Mishnah Taanit 3:4
And so too a city which has a plague or [its buildings] collapse that city fasts and they sound a blast, but those [in the places] around it fast but do not sound the alarm. Rabbi Akiva says: they sound the alarm but do not fast. What constitutes a plague? If in a city that can supply five hundred foot-soldiers and three deaths occurred on three consecutive days, behold this constitutes a plague, less than this is not a plague.
Shulchan Arukh, Yoreh De'ah 116:5
One must refrain from putting coins in one's mouth, lest it's covered with dried saliva of those afflicted with boils. He should not put the palm of his hand in his arm pit, lest his hand touched a metzorah or a harmful poison. He should not put a loaf of bread under his armpit, because of the sweat. He should not put a cooked item or drinks under the bed, since an evil spirit rests on them. He should not stick a knife in an esrog or a radish, lest one fall on its edge and die. Hagah: Similarly, he should be careful of all things that cause danger, because danger is stricter than transgressions, and one should be more careful with an uncertain danger than with an uncertain issur. They also prohibited to go in a dangerous place, such as under a leaning wall, or alone at night. They also prohibited to drink water from rivers at night or to put one's mouth on a stream of water and drink, because these matters have a concern of danger. It is the widespread custom not to drink water during the equinox, and the early ones wrote this and it is not to be changed. They also wrote to flee from the city when a plague is in the city, and one should leave at the beginning of the plague and not at the end. And all of these things are because of the danger, and a person who guards his soul will distance himself from them and it is prohibited to rely on a miracle in all of these matters.
Shulchan Arukh, Orach Chayim 4:18
The following things require washing the hands in water [after them]: One who rises from bed, goes out of the bathroom, or of the bath house, one who cuts his nails, takes off his shoes, touches his feet, or washes his head, some say: also one who goes among the dead, or touched the dead, one who cleanses his clothes of lice, has sexual intercourse, touches a louse, or touches his body with his hand. Anyone doing any of these and not washing his hands, if he is a scholar, his studies are forgotten, and if he is not a scholar, he goes out of his mind.
When Mordecai learned all that had happened, Mordecai tore his clothes and put on sackcloth and ashes. He went through the city, crying out loudly and bitterly, until he came in front of the palace gate; for one could not enter the palace gate wearing sackcloth.— Also, in every province that the king’s command and decree reached, there was great mourning among the Jews, with fasting, weeping, and wailing, and everybody lay in sackcloth and ashes.— When Esther’s maidens and eunuchs came and informed her, the queen was greatly agitated. She sent clothing for Mordecai to wear, so that he might take off his sackcloth; but he refused.
But take utmost care and watch yourselves scrupulously, so that you do not forget the things that you saw with your own eyes and so that they do not fade from your mind as long as you live. And make them known to your children and to your children’s children:
Of David. A psalm. The earth is the LORD’s and all that it holds, the world and its inhabitants. For He founded it upon the ocean, set it on the nether-streams. Who may ascend the mountain of the LORD? Who may stand in His holy place?— He who has clean hands and a pure heart, who has not taken a false oath by My life or sworn deceitfully. He shall carry away a blessing from the LORD, a just reward from God, his deliverer. Such is the circle of those who turn to Him, Jacob, who seek Your presence.Selah. O gates, lift up your heads! Up high, you everlasting doors, so the King of glory may come in! Who is the King of glory?— the LORD, mighty and valiant, the LORD, valiant in battle. O gates, lift up your heads! Lift them up, you everlasting doors, so the King of glory may come in! Who is the King of glory?— the LORD of hosts, He is the King of glory!Selah.
And it is taught in a baraita: A Torah scholar is not permitted to reside in any city that does not have these ten things: A court that has the authority to flog and punish transgressors; and a charity fund for which monies are collected by two people and distributed by three, as required by halakha. This leads to a requirement for another three people in the city. And a synagogue; and a bathhouse; and a public bathroom; a doctor; and a bloodletter; and a scribe [velavlar] to write sacred scrolls and necessary documents; and a ritual slaughterer; and a teacher of young children. With these additional requirements there are a minimum of 120 men who must be residents of the city. They said in the name of Rabbi Akiva: The city must also have varieties of fruit, because varieties of fruit illuminate the eyes.
if he then gets up and walks outdoors upon his staff, the assailant shall go unpunished, except that he must pay for his idleness and his cure.
As Rav Aḥa said: One who enters to let blood says:
May it be Your will, O Lord my God,
that this enterprise be for healing and that You should heal me.
As You are a faithful God of healing and Your healing is truth.
Because it is not the way of people to heal, but they have become accustomed.
Rav Aḥa is saying that people should not practice medicine as they lack the ability to heal; rather, healing should be left to God. Abaye responded and said: One should not say this, as it was taught in the school of Rabbi Yishmael that from the verse, “And shall cause him to be thoroughly healed” (Exodus 21:19), from here we derive that permission is granted to a doctor to heal. The practice of medicine is in accordance with the will of God.
Siddur Ashkenaz, Weekday, Shacharit, Amidah, Healing 1-3
Heal us, O Lord, and we shall be healed, save us and we shall be saved, for You are our praise. Bring complete healing to all our wounds, (Prayer for a sick person: May it be Your will in front of You, O Lord, my God and the God of my forefathers, that You quickly send a complete recovery from the Heavens - a recovery of the soul and a recovery of the body - to the the sick person, insert name, the son/daughter of insert mother's name, among the other sick ones of Israel.) for You are God and King, the faithful and merciful healer. Blessed are You, O Lord, Who heals the sick of his people Israel.
II Chronicles 16:12-13
In the thirty-ninth year of his reign, Asa suffered from an acute foot ailment; but ill as he was, he still did not turn to the LORD but to physicians.
Furthermore, with regard to the manna: The students of Rabbi Shimon ben Yoḥai asked him: Why didn’t the manna fall for the Jewish people just once a year to take care of all their needs, instead of coming down every day? He said to them: I will give you a parable: To what does this matter compare? To a king of flesh and blood who has only one son. He granted him an allowance for food once a year and the son greeted his father only once a year, when it was time for him to receive his allowance. So he arose and granted him his food every day, and his son visited him every day. So too, in the case of the Jewish people, someone who had four or five children would be worried and say: Perhaps the manna will not fall tomorrow and we will all die of starvation. Consequently, everyone directed their hearts to their Father in heaven every day. The manna that fell each day was sufficient only for that day, so that all of the Jewish people would pray to God for food for the next day. Alternatively, they received manna daily so that they would be able to eat it while it was hot and fresh. Alternatively, they received manna daily due to the hardship of carrying on the journey. They did not stay in the same place all those years, and it would have been difficult for them to carry the manna from one place to another. Therefore, the manna fell wherever they went.