When (specifically pertaining to illness, discomfort, etc.) can one be considered exempt from "positive" mitzvot (mitzvot asei)?

Question

When would it reach a degree of discomfort, illness, or other types of cases of distress that one would be exempt from fulfilling a positive commandment? For example, does the concept of "Nafal BaMishkav", meaning, a desire/need to lay down in bed be considered an "Oines" which is exempt, or would it need to be something more severe?

Can someone explain or elaborate? With Sukkah, it's very simple - if you are uncomfortable, you aren't obligated, period. I am referring to every other case of a positive Asei. Is that a standard criterion, or an individual criterion for each mitsvot, or clusters of Mitsvot?

Thank you.

Answer 1

Tefilin is a perfect example of what you are describing.

Chulin 110a:

חזייה דלא הוה מנח תפילין אמר ליה מאי טעמא לא מנחת תפילין אמר ליה חולי מעיין הוא ואמר רב יהודה חולי מעיין פטור מן התפילין

Rav Ḥisda saw that Rami bar Tamrei had not donned phylacteries, and said to him: What is the reason that you have not donned phylacteries? Rami bar Tamrei said to him: He, i.e., I, am suffering from intestinal illness, and Rav Yehuda said that one who has intestinal illness is exempt from the mitzva of phylacteries, which require a clean body, because he would have to remove them constantly to defecate.

Orach Chaim 38.1:

חולה מעיים פטורמתפילין: הגה אפילו אין לו צער אבל שאר חולה אם מצטער בחליו ואין דעתו מיושב עליו פטור ואם לאו חייב. [מרדכי וא"ח ומיי' פ"ד]:

One who is ill in his intestines is dispensed from the [commandment to wear] tefillin. Rema: "Even if he is not in pain. However any other invalid, if he is in pain due to his illness and his mind is not at ease, he is also dispensed [from the commandment]. Otherwise he is obligated."

Rambam, Tefilin 4.13:

כָּל הַפָּטוּר מִקְּרִיאַת שְׁמַע פָּטוּר מִתְּפִלִּין. חוֹלֵי מֵעַיִם וְכָל מִי שֶׁלֹּא יָכוֹל לִשְׁמֹר אֶת נְקָבָיו אֶלָּא בְּצַעַר פָּטוּר מִן הַתְּפִלִּין. מִצְטַעֵר וּמִי שֶׁאֵין דַּעְתּוֹ מְיֻשֶּׁבֶת וּנְכוֹנָה עָלָיו פָּטוּר מִן הַתְּפִלִּין שֶׁהַמֵּנִיחַ תְּפִלִּין אָסוּר לוֹ לְהַסִּיחַ דַּעְתּוֹ מֵהֶן.

One who is exempt from reading the Shema is exempt from putting on phylacteries. Those who suffer intestinal troubles or have difficulty in controlling their sphincters are exempt from the obligation of putting on phylacteries. One, who is in pain or whose mind is not calm and composed is exempt from the duty of putting on phylacteries; for the wearer must not allow his consciousness of them to wander.