The Gemara in Masechet Shabbat (22) establishes the Halacha of "Bizui Misva," which forbids treating Misvot and Misva objects disrespectfully. The source of this prohibition is a Halacha concerning "Kisui Ha’dam," the Torah obligation to cover the blood spilt by slaughtering birds and certain animals. When one slaughters a chicken, for example, he is obligated by Torah law to cover the blood with earth. The Gemara teaches that one must cover the blood using either his hand or a utensil. He should not kick earth with his feet over the blood, as this is disrespectful to the Misva. This principle extends to all Misvot: Halacha requires treating Misvot with respect and ensuring not to treat them in a degrading manner.
The Halacha of "Bizui Misva" has many practical applications. The case of "Kisui Ha’dam," for example, arises very often before Yom Kippur, when many people purchase a chicken to be slaughtered for "Kapparot." It is common for the Shohet (slaughterer) to invite the person who purchased the chicken to perform the Misva of covering the blood. (Incidentally, this Misva is quite rare for those who are not generally involved in Shehita, so it is a great privilege to perform this Misva when the opportunity presents itself.) The individual must remember to cover the blood using his hand, and not kick dirt over the blood.
Another manifestation of this Halacha is the Shulhan Aruch’s ruling (Orah Haim 651:7) that one should not wave the Lulab on Sukkot while it is in a utensil. It is improper, for example, to perform the Misva of Lulab while it is in a vase, as it gives the appearance that one does not wish to directly touch the Lulab.
Furthermore, the Rama (Rabbi Moshe Isserles, Poland, 1525-1572) writes that one should not discard old Sisit in a degrading manner, such as directly in a trash bin. Even though, strictly speaking, Sisit which are no longer used for the Misva are not endowed with any Halachic status of sanctity and may be discarded, it is proper, in the interest of properly respecting Misvot, to discard them respectfully. One should therefore place the Sisit in a bag and then place the bag in the garbage, so they do not come in direct contact with refuse. The Mishna Berura (commentary by Rabbi Yisrael Meir Kagan, 1839-1933) writes that ideally, one should try to use them for another Misva, such as making the strings a bookmark in his books of Torah.
Similarly, one should not discard the Sechach or walls of a Sukka which he no longer uses for a Sukka. Once again, they should ideally be used for another Misva. For example, one can give the wood to a Masa bakery to use as firewood for the ovens.
A particularly fascinating application of this rule appears in the Bet Halevi (work by Rav Yosef Dov Soloveitchik of Brisk, 1820-1892). When a person gives charity to a poor person, the Bet Halevi comments, the recipient obtains the status of a "Misva article" and must therefore be treated with respect. Just as one must treat Sisit and a Lulab with respect, similarly, he must show respect to a poor person, through whom the Misva of Sedaka is performed. Accordingly, one who gives charity to a poor person in a disparaging manner transgresses this prohibition of treating Misvot disrespectfully.
Summary: When one performs the Misva of "Kisui Ha’dam" (covering the blood after slaughtering), he should do so by hand, and not with his foot. One should not perform the Misva of Lulab while the Lulab is in a utensil, such as a vase. Sisit strings that are no longer used for the Misva should ideally be used for a different Misva (such as a bookmark); otherwise, they should be placed in a bag and then discarded. This applies as well to the Sechach and walls of a Sukka. When giving charity to a poor person, one must ensure to do so respectfully, even if for no other reason than the obligation to treat Misvot with respect.
