(14) Now the spirit of the LORD had departed from Saul, and an evil spirit from the LORD began to terrify him. (15) Saul’s courtiers said to him, “An evil spirit of God is terrifying you. (16) Let our lord give the order [and] the courtiers in attendance on you will look for someone who is skilled at playing the lyre; whenever the evil spirit of God comes over you, he will play it and you will feel better.” (17) So Saul said to his courtiers, “Find me someone who can play well and bring him to me.” (18) One of the attendants spoke up, “I have observed a son of Jesse the Bethlehemite who is skilled in music; he is a stalwart fellow and a warrior, sensible in speech, and handsome in appearance, and the LORD is with him.” (19) Whereupon Saul sent messengers to Jesse to say, “Send me your son David, who is with the flock.” (20) Jesse took an ass [laden with] bread, a skin of wine, and a kid, and sent them to Saul by his son David. (21) So David came to Saul and entered his service; [Saul] took a strong liking to him and made him one of his arms-bearers. (22) Saul sent word to Jesse, “Let David remain in my service, for I am pleased with him.” (23) Whenever the [evil] spirit of God came upon Saul, David would take the lyre and play it; Saul would find relief and feel better, and the evil spirit would leave him.
What is a "shoteh" [translated until now as a mentally ill person]? He who goes out alone at night, and he who sleeps in a cemetery, and he who tears his clothes.
(ט) הַשּׁוֹטֶה פָּסוּל לְעֵדוּת מִן הַתּוֹרָה לְפִי שֶׁאֵינוֹ בֶּן מִצְוֹת. וְלֹא שׁוֹטֶה שֶׁהוּא מְהַלֵּךְ עָרֹם וּמְשַׁבֵּר כֵּלִים וְזוֹרֵק אֲבָנִים בִּלְבַד. אֶלָּא כָּל מִי שֶׁנִּטְרְפָה דַּעְתּוֹ וְנִמְצֵאת דַּעְתּוֹ מְשֻׁבֶּשֶׁת תָּמִיד בְּדָבָר מִן הַדְּבָרִים אַף עַל פִּי שֶׁהוּא מְדַבֵּר וְשׁוֹאֵל כָּעִנְיָן בִּשְׁאָר דְּבָרִים הֲרֵי זֶה פָּסוּל וּבִכְלַל שׁוֹטִים יֵחָשֵׁב. הַנִּכְפֶּה בְּעֵת כְּפִיָּתוֹ פָּסוּל וּבְעֵת שֶׁהוּא בָּרִיא כָּשֵׁר. וְאֶחָד הַנִּכְפֶּה מִזְּמַן לִזְמַן אוֹ הַנִּכְפֶּה תָּמִיד בְּלֹא עֵת קָבוּעַ. וְהוּא שֶׁלֹּא תִּהְיֶה דַּעְתּוֹ מְשֻׁבֶּשֶׁת תָּמִיד שֶׁהֲרֵי יֵשׁ שָׁם נִכְפִּים שֶׁגַּם בְּעֵת בְּרִיאוּתָם דַּעְתָּם מִטָּרֶפֶת עֲלֵיהֶם. וְצָרִיךְ לְהִתְיַשֵּׁב בְּעֵדוּת הַנִּכְפִּין הַרְבֵּה:
(9)A shoteh's testimony is invalid on a biblical [level] because he is not eligible [to perform] Mitzvot. This [does not refer to] only to a shoteh who goes naked, breaks things, and throws stones, rather anyone whose sanity is impaired and finds his intellect constantly confused on some point even if he can ask [questions] and converse on topics regarding other things. An epileptic is considered a "shoteh" during a seizure, and considered healthy at all other times, whether he is someone who gets seizures at predictable periods or the seizures happen randomly. This is only [true] if he is not always confused for there are epileptics who are mentally impaired even when not experiencing seizures. And one must consider the testimony of someone who has lots of seizures [on a case by case basis].