כאילו מתחייב בנפשו (אבות, פרק ג)

All may slaughter, and their slaughtering is valid, except a deaf-mute, an imbecile or a minor, lest they mess up [the animal] through their slaughtering. And if any of these slaughtered while others were standing over them, their slaughtering is valid. That which is slaughtered by a non-Jew is a nevelah and defiles by carrying. If one slaughtered at night, and also a blind man that slaughtered, the slaughtering is valid. One who slaughtered on Shabbat or Yom Kippur, even though he is liable for his own life, the slaughtering is valid.

Rabbi Elazar of Bartotha said: give to Him of that which is His, for you and that which is yours is His; and thus it says with regards to David: “for everything comes from You, and from Your own hand have we given you” (I Chronicles 29:14). Rabbi Jacob said: if one is studying while walking on the road and interrupts his study and says, “how fine is this tree!” [or] “how fine is this newly ploughed field!” scripture accounts it to him as if he was mortally guilty.

Rabbi Hananiah ben Hakinai said: one who wakes up at night, or walks on the way alone and turns his heart to idle matters, behold, this man is mortally guilty.

Rabbi Dostai ben Rabbi Yannai said in the name of Rabbi Meir: whoever forgets one word of his study, scripture accounts it to him as if he were mortally guilty, as it is said, “But take utmost care and watch yourselves scrupulously, so that you do not forget the things that you saw with your own eyes” (Deuteronomy 4:9). One could [have inferred that this is the case] even when his study proved [too] hard for him, therefore scripture says, “that they do not fade from your mind as long as you live” (ibid.). Thus, he is not mortally guilty unless he deliberately removes them from his heart.

When man contemplates concerning these things, and perceives all creatures, whether angel, sphere, or man the likeness of himself, and discovers the wisdom of the Holy One, blessed is He! in all beings of form and in all creatures, his love for the Omnipresent increases and his soul and body thirst and yearn to love Him, blessed is He! and, fear and terror, because of his own insignificance, shortcomings and levity seize him when comparing himself to one of the great and holy bodies, verily so to one of the pure forms, separated from bodies of clay, which never joined a body of clay. He then will find himself likened to a vessel full of shame and disgrace, empty and wanting.²Shabbat, 31b. G.