Safeguarding the matzot to be used for fulfilling the mitzva of eating matza on the Seder night has two meanings: being extra vigilant to prevent it from becoming ḥametz and intending that the making of this matza is for the sake of the mitzva of eating matza (“le-shem matzat mitzva”). It is therefore necessary that the matza be kneaded and baked by Jews who are halakhic adults, who can be relied upon to focus their actions for the sake of matzat mitzva, not gentiles, minors, or the mentally unfit, since they cannot be relied upon to have the proper intent (She’iltot, Rashba).
Some dispute this second meaning. In their view, the mitzva of guarding the matza requires extra vigilance to prevent the matzat mitzva from becoming ḥametz but not that the matzot are baked with special intent. Thus, gentiles and minors are fit to knead and bake matzat mitzva, as long as an adult Jew supervises their work, ensuring that they work quickly and that the dough does not become ḥametz. His supervision should be for the sake of matzat mitzva (Ra’ah).
In practice, at the time of kneading one should take care to fulfill both meanings of “safeguarding.” Thus, one must insist that Jews knead and bake the matzat mitzva, taking care that the dough does not become ḥametz and intending that the matza be for the sake of the mitzva. However, at the time of harvesting and milling, the first meaning is sufficient. Thus, the wheat may be harvested and milled by gentiles as long as a Jew stands nearby and supervises their work, ensuring that it does not become ḥametz (SA 460:1; MB and SHT 4 ad loc.).
Le-khatḥila, one should say out loud, when starting to work on matzot, that all the work is being done for the sake of producing matzat mitzva; be-di’avad, it is sufficient that he thought it (BHL 460:1, based on Pri Megadim). He should also have in mind that it is for the matzat mitzva that one eats on Seder night, but if he had in mind that it is for matza for Pesaḥ, he has fulfilled the obligation (SAH 453:14).
According to Baḥ and Eliya Rabba, those who believe that the guarding must begin at the time of the harvest (see the previous section) also require a Jew to harvest and mill the wheat le-shem matzat mitzva. Some are meticulous about this in practice. (According to those who maintain that turning on a machine does not constitute proper intent – see the next section – the harvesting and milling must be done by hand, not with agricultural machinery; very few people insist on this.)
Taz explains that the harvesting and milling need not be done with intention for the sake of matzat mitzva; therefore, one may have a gentile harvest and mill the wheat, provided that a Jew supervises and ensures that the wheat does not become ḥametz. The need to have Intentions during specific actions begins at the time of kneading, so it is necessary to ensure that a Jew performs the kneading and baking (according to most poskim). Consequently, SA 460:1 rules that gentiles are unfit to perform the kneading or baking of the matza. BHL 460:1 s.v. “ein” states that the universal custom is to be lenient in accordance with Taz, that gentiles harvest and mill the wheat under the supervision of a Jew. So states Ḥok Yaakov and SAH 453:16. Matza that is made this way is called “shemura mi-she’at ketzira” – supervised from the time of the harvest.