(Mrs. Secular Jew has already heard this, so she can tune out)
For the current rabbinical school seminar at IISHJ, we read sections from the Kitzur Shulchan Arukh (“KSA”), a mid-to-late 1800s halakhic collection compiled by R. Shlomo Ganzfried. It’s a code in the sense that it follows the general scheme of R. Joseph Karo‘s Shulchan Arukh, but KSA is not generally intended to be used in reaching halakhic decisions as much as it is intended to serve as a guide for the average person in observing halakhah.
In any case, KSA at 128:13 has a description of what one should do on Erev Rosh Hashanah when visiting the graves of tzadikim to seek additional merit for one’s repentance during the Days of Awe. Setting aside the complications involved with this sort of intercessory prayer (one isn’t supposed to pray to the tzadikim so much as to God seeking the benefit of their merit, or, if you’re a Chabadnik, to ask the tzadikim to pray on your behalf), there’s an interesting bit of minhag in there: “When placing one’s hand on the grave (i.e., the gravestone), one must put only his left hand (on it), and not his right.”
Neither printing of KSA that I own (the Metsudah version with English translation on facing pages and an all-Hebrew edition from 1987 or thereabout) has any annotation or commentary about this. Some online searches on this didn’t turn up a rationale either. Those searches actually turn up only KSA as the source for this practice. (See here and here.) And the cross-indexing in the back of the Hebrew edition of KSA, which points to the relevant sources in the Shulchan Arukh and Mishnah Berurah, didn’t lead to any enlightenment–those sources don’t give any hint.
Which means that this is likely entirely minhag. Not just that, but it’s kind of bubbe meise.
Ask yourself: why the left hand?
- Jewish Superstitions (thestarryeye.typepad.com)