456. Tzitzis Made By a Non-Jew
Tzitzis 1:12
Tzitzis made by a non-Jew are invalid because Numbers 15:38 says, “Speak to the children of Israel... and you shall make tzitzis for yourselves” (so the children of Israel should make tzitzis for themselves). If a Jew made tzitzis without the intention that they would be used for the mitzvah, they are nevertheless valid. Tzitzis made from existing tzitzis (see next halacha) are invalid.
Tzitzis 1:13
Tzitzis made from existing tzitzis means taking the corner of a garment that already has tzitzis attached to it and sewing it onto another garment. If this were done, it is invalid, even if that corner of a garment is a square cubit in size. This is invalid because Numbers 15:38 says, “You shall make tzitzis for yourselves,” meaning that we should make tzitzis, not repurpose those that were made previously. If one were to do this, it would would be as if the mitzvah “just happened.” However, it is permitted to remove both the white and blue stings from one garment and tie them on another.