Know! because people are of little faith they need fasting—i.e., difficult devotions. For it is certainly known that it is possible to serve God with all things, because the Blessed Holy One does not make unreasonable demands of His creations (Avodah Zarah 3a).

Nevertheless, when difficult devotions are necessary, it relates to what our Sages, of blessed memory, taught (Sanhedrin 74a-b) : In a time of religious oppression, even to change one’s shoelaces is a matter of “be killed rather than transgress.” It follows, that although it is actually not right that he be killed for this, nevertheless, it is a time of religious oppression, and they are powerful and in particular want to cause him to leave religion and bring him to heresy, God forbid. He must therefore give up his life even for something minor.

Idolatry and atheism are the concept of “nor is there any ruach (breath) in their mouths” (Psalms 135:17)—they have no ruach (spirit) in them whatsoever. Those of little faith correspond to “shortness of spirit,” which resembles a middle ground. In other words, they lack complete faith, which corresponds to extending one’s ruach, as brought elsewhere; even so, they are not complete heretics, who have no ruach whatsoever. Rather, they resemble a middle ground. Their ruach is short, the concept of “because of a shortness of spirit.”

This is the meaning of “because of a shortness of ruach and avodah kashah (hard labor)” (Exodus 6:9). Because they conceptually correspond to “shortness of ruach,” on account of their being of little faith, they therefore need avodot kashot (difficult devotions) and fasting, as mentioned above. Just as in a time of religious oppression, which is the utter corruption of faith, one even has to actually give up his life even for something minor, so too when there is “smallness” and blemished faith, one has to perform difficult devotions.

Now, there are many levels of little faith. There are even tzaddikim of little faith, as our Sages, of blessed memory, interpreted the verse: “For who has despised the day of small things” (Zechariah 4:10)—who caused the tzaddikim…? (Sotah 48b).