Igrot Kodesh · Letter 779 — Tzedakah
Volume 4 · Letter 14 · [Entre Roch Hachana et Yom Kippour 5711]
[Between Rosh Hashanah and Yom Kippur 5711]
He who goes up to the Torah [1] also says "Chazak, Chazak v'Nischazek" [2]. This is not an interruption, since this formula is directly linked to the conclusion. You will consult, on this subject, the Shulchan Aruch of the Alter Rebbe, chapter 167, §9.
He too says this phrase, since in the version we accept it is clearly stated 'v'Nischazek' [3].