The Torah Portion of Tzav
"And he shall remove his garments and he shall put on other garments." (Vayikra 6:4)
Rashi explains, garments in which he was dressed when he cooked a pot of food for his master, he should not pour while dressed in them, a cup of wine for his master. The Maharsha brings from this a proof, that a person should change his clothes in the honor of Shabbat to garments which are appropriate and clean, just as the Cohen would change his clothes at the time of his service, and would not use the same clothes that he wore when he was removing the ashes from the altar. Thus it is necessary to change clothes for Shabbat, and not use the same clothes that one wore on Erev Shabbat while preparing for Shabbat.
"Matzot shall be eaten in a holy place." (Vayikra 6:9)
This is a hint to the Matzot that are eaten on the night of Passover, that they should be in a holy place. That is to say, that one should sanctify his mouth, for that is the place of eating the Matzot. This is also hinted at by the word "Pharoah", which in Hebrew has the same letters as Peh-Ra (an evil mouth), and the rectification for this is Pesach, which in Hebrew is similar to the Hebrew words Peh-Sach (a mouth which speaks). One should speak only words which are good and holy, for everyone who increases speaking about them (i.e., the miracles of Passover) is praiseworthy. And the opposite is also the case; someone who doesn't speak good words, G-d forbid, is not praiseworthy.
The Miracle on Shabbat Hagadol
The Shabbat before Passover is called Shabbat HaGadol, the Great Shabbat, because of the miracle which occurred on it: the children of Israel took sheep, and tied them to their beds, in preparation for slaughter. Even though the Egyptians were very angry that the Jews were going to slaughter sheep, since they worshiped the sheep as idols, they didn't say anything about it to the Jews because they had developed a great fear of the Jewish people.
The Rabbi's Drasha on Shabbat Hagadol
Another reason that it is called Shabbat HaGadol, the Great Shabbat, is because then a Gadol (great person) speaks before the people about matters pertaining to the holiday, and therefore it is called "Shabbat HaGadol". [That is, the Gadol speaks about how to be careful to avoid the slightest bit of Chametz on Pesach.] Everyone who is careful about avoiding the slightest bit of Chametz on Pesach is promised that he won't sin all year. (Ba'er Heitev Siman 447) Why are we stringent on Pesach about the slightest bit? To hint that if the congregation of Israel had remained in Egypt the slightest bit more time, they would have entered the 50th gate of impurity.
"Yom Hashem HaGadol." (Malachi 3:24)
Another reason it is called "Shabbat HaGadol" is because the Haftara of this Shabbat ends with the words "Yom Hashem HaGadol..." (the Great day of Hashem).
Why do we have this remembrance of the miracle of Shabbat HaGadol precisely on Shabbat?
Even if the Jews had done so (taken the sheep) on one of the days of the week, it would also have been a miracle. Therefore the remembrance should have been set for the 10th day of Nissan, when they were commanded about it. However, because Miriam passed away on the 10th day of Nissan, as is explained in Shulchan Aruch Siman 580, they didn't want to set the remembrance for that day, but rather on the day of Shabbat, for in that year the 10th of Nissan was on Shabbat. (Shulchan Aruch HaRav)
The Torah Portion of "Tzav" has 97 verses. There are 9 positive commandments and 9 negative commandments.The Haftorah is "V'arvah L'Hashem" (Malachi)
L'ilui Neshamat HaGaon HaTzaddik R' Gershon Avigdor Ben R Chaim ztz"l
In Nissan we were redeemed, and in Nissan we are to be redeemed in the future. (Rosh Hashanah 11a)
May we merit to eat from the Pesachim and the Zevachim (the Passover sacrificial offerings)