We were a unity at Har Sinai to receive the Torah. Achdus Yisroel is a term we use to deschribe why we should have Ahavas Yisroel. In essence we are one, as a people with one neshama.
The two important principles of Achdus Yisroel and Ahavas Yisroel should be common practice on Shabbos before Shavuos, to prepare for the giving of the Torah as one people.
During the Sefiras HaOmer we count 49 days -7 weeks. The Jewish people are represented by a seven- branded menorah - symbolic for the seven Sefiros and the seven levels of Divine service. The unity of the seven- brances of the Jewish neshama who interact which each other, do symbolize the seven weeks.
The period of Sefiras HaOmer serves as a preparation for Shavuos. Matan Torah is depended on the participation of every single Jew.
Parsha Bamidbar has a particular relevance to Shavuos. Every Parsha has a connection with the time of the year when it is read, and Bamidbar is usually read on the Shabbos before Shavuos. And in particular, Shavuos, which commemorates HaShem giving the Torah to the Jewish people, is called : "The Chasene of Yisroel to HaShem, " and on the Shabbos before a chasene the chosson is called to the Torah as a preparation for the chasene. So Bamidbar is a preparation for that special connection between HaShem and the Jewish people upon Matan Torah.
In the opening words of parsha Bamidbar, HaShem tells Moshe to count the entire community of all tribes;
" Alongside him there shall be one man for each tribe" - from each of the 12 tribes, one man was to assist in the count alongside Moshe and Aharon.
Counting the Jewish people in order to know their number, the parsha explains that the Jewish were beloved to HaShem. He counted them regularly. When the Jews were numbered as one entity, which revealed the Jewish gualities in individual differences, but the essential quality of the Jewish neshama are in all Jews the same.
Even though there are qualities of the individual, every Jews is a part of a single whole. Every Jew was counted and equal to all other Jews. The individual tribes are part of the Jewish people as a whole.
May we individually, and in unity continue to accept the responsibility fulfilling the ultimate goal of HaShem's plan in creation.To help humanity we have to reach out to achieve absolute oneness with HaShem.
Shabbos Achdus is a desginated Shabbos before Shavuos, during which the Rebbe encourage all Jews to keep at least one Shabbos in unity. This mirrors the unity of the Jewish people at Har Sinai. Jewish unity strengthen Ahavas Yisroel - loving our fellow Jew.
In 1986 the Rebbe made a Bakosha Nafshis - personal request, for all communities to organize farbrengens during the afternoon of Shabbos Parsha Bamidbar.
The purpose of these farbrengens are to bring unity among Jews of all backgrounds to encourage k'Ish Echad B'Lev Echad- one people with one heart, which create unity, harmony and a shared purpose.
The Shabbos before Shavuos will strengthen Jewish unity. The Torah depends on unity.
We are the last generation of golus and the first generation of geulah, and HaShem is helping us to see that the world itself is helping and leading it towards the geulah.
May we be zoche to see the coming of the Moshiach soon, Omeyn.