Our page discusses if this is a general principle or not: yes, performance of a time bound mitzvah overrides the Shabbat – but do the preliminaries (that is, the preparations needed) supersede in all cases as well?
R. Hiyya b. Abba said in R. Johanan's name: Not in respect of everything did R. Eliezer rule that the preliminary preparations of a precept supersede the Sabbath. . .
What follows is a long examination of a series of mitzvot which do take precedence over the Shabbat laws:
- The two loaves offered on Shavuot (Lev. 23:17) – note: only in Temple times
- Lulav on Sukkot (Lev. 23:40) which may be carried in public
- Sukkah (Lev. 23:42)
- Matzah on Passover
- Shofar on Rosh Hashanah (Lev. 23:24)
All these are found to include not only the performance of the mitzvah, but the preparations as well. So why doesn’t R. Eliezer make it a general principle?
Said R. Adda b. Ahabah: It is to exclude (inserting) fringes for one's garment and (affixing) mezuzah for one's door
Why are these particular mitzvoth excluded? R. Joseph says because there is no fixed time for them. Abaye counters that this is not a very good argument - since there is no fixed time, any time (including, presumably Shabbat) is appropriate!
Rather said R. Nahman b. Isaac others state, R. Huna son of R. Joshua: Because it is in one's power to renounce their (tallit, mezzuah’s) ownership.
General principle or no, preparation for mitzvah is part of mitzvah.