Shabbos Parshas Vayechi and Shabbos Chazak Customs

It is customary to stand when the last possuk of the Chumash is read.

After the baal korei finishes reading the seventh aliyah, the entire congregation recites aloud, “Chazak chazak venischazek!” This is then repeated by the baal korei. (The one receiving the aliyah says these words as well.)

The Rebbe encouraged the minhag that the gabbaim prepare a kiddush/farbrengen on Shabbos Chazak. At this farbrengen, share words of Torah, accept positive hachlatos, and celebrate the conclusion of the Chumash (similar to Simchas Torah).

On Shabbos Chazak, every Jew should strengthen himself, his family, and all those in his vicinity in all matters of Yiddishkeit, Torah, and mitzvos.”
-Sefer Hasichos 5750, Vol. 1, p. 233