John Trapp on Psalms 137:5

Verſ. 5 I[illegible: 1 letter] I forget thee, O Jeruſalem] As I might ſeem to do, ſhould I herein gratifie theſe Idolaters; or otherwiſe obey them, rather than God. The Jews at this day, when they build an houſe, they are, ſay the Rabbines, to leave one part of it unfiniſhed, and lying rude, in remembrance that Jeruſalem and the Temple are at preſent deſolate. At leaſt they uſe to leave about a yard ſquare of the houſe unplaiſtered, on which they write,Leo Modena of the ri[illegible: 1 letter]es of the Jews. in great letters, this of the Pſalmiſt, If I forget Jeruſalem, &c. or elſe theſe words Zecher lechorban, that is, The memory of the deſolation.

Let my right hand forget] Fiat abalienata atque emortua, Let it bee paralyticall and uſeleſs, unfit to touch the harp.