If a sheet tore
1. If a sheet of a sefer Torah tore, at the top or at the bottom, and the tear was in the margin but did not extend into the text, it may be read from just as if it had not torn, even without being repaired, but it ought to be repaired. If the tear extended into the lettering, even into just one line, it may not be read from until it has been fixed – this applies also if it went into two lines. But if the tear went into three lines, it may not be stitched, but the sheet must be replaced. When does this apply? When it is old and the tanning is no longer recognisable and it will be a blemish. But if its tanning was still recognisable it may be sewn, even if the tear extends into three lines. Our sifrei Torah may be sewn even if they are old and the tear extends into three lines, since the parchment is white and the sinew is white and the seam is not really visible.
2. If the tear went into more than three lines, it may not be sewn under any circumstance and the sheet must be replaced. Neither may it be sewn if the tear was only between columns, if the tear would have gone into three lines had it been in the writing.
3. All the sewing under discussion must be done exclusively with sinew, and is only of use if it does not damage any letters. If it damages or divides a letter it is of no use, and one must take care not to put his needle into the writing, but must keep it outside the writing.
4. Some say that one may use a patch to repair any tear which could be sewn (provided the glue is obtained from ritually pure animals), and some are more lenient and say that a patch may be used even where sewing would be forbidden; one may rely on this opinion in pressing circumstances. When patching, one must also take care not to break any letters, since if a letter is broken sticking something behind it does not help.
5. It is the custom when there is a hole in the klaf, or if some mistake had to be cut out, for scribes to attach a patch on the outside, to make it very nicely and then write whatever is lacking on the patch. Some forbid this. If one is stringent with his own sefer Torah this is extremely praiseworthy, but the widespread custom is to permit it, and this practice is supported.
6. He may do this only if he writes the whole letter on the patch; if he writes part on the patch and part on the sheet, it is invalid. Further, it is invalid even if the whole letter is written on the sheet but extends very slightly onto the patch, because the patch does not count towards surrounding the letter with blank klaf; the letter must be surrounded with the klaf from the sheet, and not from the patch. A letter written on a patch must be surrounded with the blank klaf of the patch, and not of the sheet.
7. One must also take great care to stick the patch on firmly before writing on it; he must not write on the patch first and then stick it on. So too if it had been written on and become detached; it does not help to stick it back on with the writing (see above, 11:13).
8. If one needs to mend a sefer Torah with a patch, he is not prohibited from using a patch made of klaf even if the sefer was made of gevil (see below, 25:3, for whether one may cut from the margins to make repairs).
9. If one is replacing worn-out sheets, he must replace three, even if only one or two actually need it, since the replacements will not look the same as the old ones, and if he doesn’t put in at least three the replacement will make the sefer look speckly. This applies only when the sefer is old and a new sheet would look conspicuous, but if a sheet had to be replaced at the time of writing, a new sheet isn’t going to look out of place, so he need only replace the invalid one (Beur Mordekhai at the end). The new sheet should measure the same as the original, and the original scribe should write it if possible (Sha”kh).