During the Farbrengen of Shabbos Parshas Toldos 5741, the Rebbe said:
“It is now appropriate to talk about the education of Jewish children.
On Chanukah there is a special emphasis regarding the Jewish children: The Acharonim bring down a custom which connects Jewish children with the idea of Tzedaka – that on Chanukah Jewish children should give Tzedaka.
Surprisingly we don’t see this custom being adhered to today, and at least from now and on, they should follow said custom.”
After Shabbos, when the Va’ad Hanochos Hatmimim prepared this Sicha to print, they were unable to find a source for this custom, and more so – the Magen Avraham writes that the poor children had a custom to go from door to door to collect money, the exact opposite of what the Rebbe said!
The Rebbe responded to them:
“On the word “Acharonim” – After the reference to the (Magen Avraham) add: a reference to the custom that the students would bring to their teachers (their salary? Chanukah Gelt?) on the days of Chanukah, and therefore they are called . .” and added that they should speak with the librarian R’ Chaim Lieberman and find out the exact source.
The editors then wrote a revised version of this footnote, adding the source that they found, the book “Chemdas Yomim,” The Rebbe crossed out the source and rewrote the sentence to read as follows:
“It is also brought down the custom which spread to various communities, that the children bring money to their teachers on Chanukah together with other presents.”