Tefillin and mezuzah; writing in sequence
1. Tefillin and mezuzot must be written in sequence, and if they were written out of order, whether paragraphs, words or letters, they are invalid. Consequently, if one found he had omitted a letter, there is nothing he can do unless it is possible to erase all the subsequent words (if there isn’t a Name amongst them), fill in the missing letter, and rewrite all the part he had erased.
2. If there was an extra letter at the beginning or end of a word, it may be erased, but not if it was in the middle of the word (since its erasure would make the one word appear like two words) unless it is possible to extend the letter before it, as for instance if he wrote לאבותיו where he should have written לאבתיו; he can erase the vav and extend the beit to fill the space. He may also thicken the letters before and after the gap, as this isn’t a significant change to the letters.
3. If a letter was not written correctly, or subsequently became damaged, such that it didn’t have its form, for instance if the leg or face of aleph touched its roof, or the legs of hey or kuf were joined to the bodies (these problems cannot be fixed by separating the stuck parts, but the form of the letter must be nullified and written afresh, since otherwise it is ḥak tokhot, as explained in chapter 8); or a letter was divided into two parts (whether during the writing or subsequently) such as tzaddi as yud and nun, shin as ayin and yud, mem petuḥa as khaf and vav, lamed as khaf and vav, or a flat-topped ḥet where the left leg had become detatched and resembled hey, and all similar cases where the division makes it seem like another letter, correction if one had written subsequent letters constitutes writing out of sequence, even if a child read them correctly, and they are invalid.
4. However, if the form of the letter remains despite having a slight break – for instance if the yuds of aleph, shin or ayin, or the leg of tav didn’t touch the roof – and a child read them correctly (and also beit or dalet if they are separated by a similar narrow gap from the roof), they are invalid until they are fixed (as explained in chapter 5:3) but nevertheless may be fixed after one had written subsequent letters, since as the form remained, their repair does not constitute writing out of sequence. If the hump of ḥet didn’t join the two sides but the break wasn’t immediately obvious, it may be fixed when one had written subsequent letters even if a child read it as two zayins, because children aren’t used to seeing this type of ḥet (concerning a ḥet made as dalet and zayin, see 8:11). There are those who suspect that all this may constitute writing out of order. Even though the tradition is to be lenient, one should still be very careful about his writing so that he will not need to invoke these leniencies (Melekhet ha-Shamayim). It seems to me that if mem setuma or samekh became separated, they may not be fixed after one had written subsequent letters even if a child read them correctly, because it may be writing out of sequence.
5. We have already seen (in chapter 5) that yud must have a tag on its upper left, a prickle on its lower left, and a leg on its right. If one finds, in tefillin or mezuzot, that it is missing the right leg, it is not yud even if a child reads it as yud, and fixing it after one had written on constitutes writing out of sequence. However, it is still yud if it is missing the prickle, and therefore this may be added afterwards if necessary, but the scribe should take care to write it in before writing further, as there are authorities who say that yud is invalid without the prickle, so adding the prickle afterwards would constitute writing out of sequence; even though we are customarily lenient, one should be careful. This is also the rule for the tag on the upper left (Melekhet ha-Shamayim).
6. We have already explained (8:16, see there) that letters which are stuck together may be separated provided the letter forms were not altered, and it seems to me that therefore if one finds two words so close together that they appear as one – for instance עלכן – he may, if he can, scrape a little away from the lamed and a little away from the khaf, so as to make it appear as two words.
7. If one wrote a word twice, he may erase it, and not worry that this will create a setuma paragraph break (according to Rabeinu Tam, who holds that three letters constitute such a break). In chapter 11:9 we explain that he should erase the second word. However, if there is a dalet, reish, beit, or other extendable letter before the first word, he should erase the first word and extend the letter so as to satisfy Rabeinu Tam’s opinion also. If erasing the extra word leaves a space of nine letters (yuds), which everyone agrees is a paragraph break, he should extend the letter before it if at all possible, even if it is hey or kuf, where extending them would take the roof far beyond the leg; this is permitted since there is no other way around it (in 5:5 I explain that one should test this with a child), as erasing the leg and writing it in at the end of the roof would be writing out of sequence. However, if it is possible any other way, this hey or kuf is not valid, as explained in chapter 5.
8. If one wrote השמרו twice, he may erase the vav from the first one and the השמר from the second, and extend the reish from the first to the remaining vav to make one word, and so in similar cases, even if the second word isn’t one which belongs in tefillin or mezuzot at all. The Perinciple is that anything retaining the form of a letter, even if it is invalid for some other reason, may be extended to make the writing valid, and does not constitute writing out of order.
9. If a letter had faded, one may rewrite it provided it was still appropriately black, and this isn’t writing out of sequence, since the letter was still valid and the new ink is only to brighten it and strengthen it to stop it getting worse. However, if the letter had gone red, or had otherwise stopped being black, rewriting doesn’t help because it counts as writing out of order (see Excursus 7).
10. Since tefillin and mezuza must be written precisely in sequence, one should check over what he has written so far before writing a Name (which may not be erased; see ch. 11) so that it will not have to be set aside. Similarly, one should check each portion of the tefillin very carefully, several times, before going on to the next, because if there is a mistake in one it will invalidate all the subsequent paragraphs, and one should take pains to avoid this.
11. One should not superscribe words in tefillin and mezuzot, even if they are written in sequence. For example, if one needed to write מימים ימימה and realised that he wasn’t going to have enough space left to make it petuḥa, and so superscribed ימים, and finished up with ימימה on the line below it, it would be invalid (see Excursus 8).