Q. What is the source for the ceremony of placing and dedicating a matzeva, is it an obligation? If the ceremony was postponed (see question above), does the monument have to stay covered until the ceremony?
A. An early source for hakomas hamatzeiva is Yaakov Avinu erecting a monument on Rochel’s grave (Bereishis 35: 20). Mishna (Shekalim 2: 5) establishes that obligation and payment dues, to erect a tombstone as asserted by the Tur, Shulchan Aruch (Y. D. 348: 2) and Teshubas Horashbo (56). The Zohar, the Arizal and Sefer Chassidim (738) also place great importance and significance on the monument named nefesh or soul.(See Gesher Hachaim, Kol Bo and others).
Nitei Gavriel (Avelus 2: 67: 3) writes that “after researching all sforim dealing with the traditions of communities, chevros kadishos, avelus and related topics, he could not find a source for the order of the ceremony of hakomas hamatzeiva.” He mentions, what is actually said and recited, depends on each community and the sidurim and similar texts they use.
Horav Shlomo Miller’s opinion is that the custom that some have to cover the matzeiva with a cloth or similar before the dedication ceremony when it is unveiled, has no basis on Halacha or our traditions.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a