The First Mishna In Yoma

The first mishna in Yoma teaches that 7 days before Yom Kippur the Kohen Gadol is separated from his home and we appoint a substitute kohen gadol for him lest he become tamei. שבעת ימים קודם יום הכיפורים מפרישין הכהן גדול מביתו ללשכת הפרהדרין ומתקינין לו כהן אחר תחתיו שמא יארע בו פסול.

When one reads a holy text, every word has significance. So let us be "medayek":

1] Why שבעת and not שבעה. If I would have written the mishna I would have written שבעה because that is the regular way of writing 7.

2] Why does it say כהן אחר - it would have been enough to write מתקינין לו כהן and we know that it is another kohen.

3] Why does it say מתקינין לו we set aside for him. It is not for him but for all of the Jewish people, so the word לו is superfluous.

Woops - have a chavrusa on skype now. Hope to get to the answers later.... In the meantime you can ponder these points.

[From last nights weekly iyun daf yomi shiur from the Rebbe Shlita]