5735-1975, for the first time, the Rebbe held a farbrengen on a weekday to mark the fifteenth of Av. At the end of the farbrengen, he distributed three dollars to each person with the request that the money be used “towards the mitzvah campaigns and especially the campaign for lighting Shabbat candles.”
1. Sichot Kodesh 5735 vol. 2 p. 393