DEUT1128 The reward of [even] a light mitzvah is great and wondrous, immeasurably so and beyond one's calculations [Hosea 2:1]. Observe the nature of shiluach ha'ken [i.e., the mitzvah of sending the mother bird away from the nest before removing the chicks or eggs [this and next verse], whose fulfillment requires no effort and a little monetary outlay. The pasuk says in reference to it (Devarim 22:7), "... so that it may be well with you and that you live a long time." Our Sages, z"l, commented (Chulin 142a), "Rabbi Yaakov said: There is no mitzvah in the Torah, [even] a light one [the reading in our Talmud is, "where its reward is written by it."] that the resurrection of the dead does not depend on it. For the pasuk says regarding shiluach ha'ken: 'So that it be good for you [and you have length of days].' 'So that it be good for you'--in the world that is entirely good; 'and you have length of days -- in the world that is forever long" [I.e., the World to Come, which is entirely good and forever long." If the Torah says this concerning a light mitzvah, which is like an issar [i.e., whose fulfillment requires little monetary outlay (Rashi). An issar was a copper coin of relatively little value; there were eight prutos to an issar. See the Second Gate, note 106.], how much more is this applicable to the more weighty mitzvos.