Commentaire sur Houlin 12:5

מצוה שהיא כאיסר – that there is no loss of money in it, other than a small amount.

One may not take the mother with the young even for the sake of purifying the metzora. One might have thought that if one needs a bird for the purification process of the metzora (one with skin disease) that it would be permitted to take the mother with the young. This purification process requires two birds (Leviticus 14:4). The mishnah states that this is prohibited one may not transgress one commandment in order to observe another.

If in respect of so light a commandment, which deals with that which is but worth an issar, the Torah said, “In order that you may fare well and have a long life”, how much more [must be the reward] for the observance of the more difficult commandments in the Torah! The mitzvah of sending away the mother bird is a relatively inexpensive mitzvah a bird is on average worth only about an issar. Thus the person who shoos the mother bird away has lost only an issar, a tiny amount of money. Nevertheless, the Torah states that he will receive a reward of having a long life. The mishnah ends with a note of encouragement, that if such a great reward is received for such an easy commandment, how much greater must be the reward for observing more difficult, and costly, commandments. Congratulations! We have finished Tractate Hullin! It is a tradition at this point to thank God for helping us finish learning the tractate and to commit ourselves to going back and relearning it, so that we may not forget it and so that its lessons will stay with us for all of our lives. Tractate Hullin was full of interesting commandments, many of which still have relevance in our lives. For those of us who eat meat (or fowl) learning Hullin is an opportunity to reflect on the meaning of taking a life in order to receive nourishment. The tractate is full of other commandments that are concerned with how we relate to killing animals in order to eat them, for instance the prohibition of killing a mother and child on the same day, or the commandment to cover the blood of a slaughtered wild animal or bird. It also dealt with the prohibition of cooking meat and milk, a practice that is to this day of great relevance in how a traditional Jew leads his/her daily life. I hope that you have enjoyed learning Hullin. In my opinion it is one of the most interesting tractates that I have learned. Tomorrow we begin learning Tractate Bechorot.