פרקי אבות חבורה ז

Nittai the Arbelite used to say: keep a distance from an evil neighbor, do not become attached to the wicked, and do not abandon faith in [divine] retribution.

It is natural for a man's character and actions to be influenced by his friends and associates and for him to follow the local norms of behavior. Therefore, he should associate with the righteous and be constantly in the company of the wise, so as to learn from their deeds. Conversely, he should keep away from the wicked who walk in darkness, so as not to learn from their deeds.This is [implied by] Solomon's statement (Proverbs 13:20): "He who walks with the wise will become wise, while one who associates with fools will suffer." Similarly, [Psalms 1:1] states: "Happy is the man who has not followed the advice of the wicked."A person who lives in a place where the norms of behavior are evil and the inhabitants do not follow the straight path should move to a place where the people are righteous and follow the ways of the good.If all the places with which he is familiar and of which he hears reports follow improper paths, as in our times, or if he is unable to move to a place where the patterns of behavior are proper, because of [the presence of] bands of raiding troops, or for health reasons, he should remain alone in seclusion as [Eichah 3:28] states: "Let him sit alone and be silent."If they are wicked and sinful and do not allow him to reside there unless he mingle with them and follow their evil behavior, he should go out to caves, thickets, and deserts [rather than] follow the paths of sinners as [Jeremiah 9:1] states: "Who will give me a lodging place for wayfarers, in the desert."

That is also taught in a baraita: This is what the scrupulous people of Jerusalem would do: They would not sign a document unless they knew who was signing with them, and they would not sit in judgment unless they knew who was sitting with them, and they would not join a meal unless they knew who was reclining, i.e., eating, with them.

A man’s fears become a trap for him,But he who trusts in the LORD shall be safeguarded.

...if one does not place his trust in G-d, he will place his trust in something else, and whoever trusts in something other than G-d, the Al-mighty will remove His providence from such a person, and leave him in the hands of the one he trusted, and he will be as it was written: "For My people have committed two evils; they have forsaken Me, the spring of living waters, to dig for themselves cisterns, broken cisterns that do not hold water" (Yirmiya 2:13), "They exchanged their Glory for the likeness of an ox eating grass" (Tehilim 106:20),"Blessed is the man who trusts in the L-ord; the L-ord shall be his refuge" (Yirmiya 17:7), "Praiseworthy is the man who made the L-ord his trust, and did not turn to the haughty and those who turn to falsehood." (Tehilim 40:5), "Cursed is the man who trusts in man, who makes flesh his strength and whose heart turns away from the L-ord" (Yirmiya 17:5).