"Rest in peace" is "Gorffwys mewn hedd".
'(May they) rest in peace' would be:Corffwys mewn heddorYn gorffwys mewn hedd.
Gorffwys mewn hedd
Gorffwys mewn hedd nain a taid. (northern Welsh) Gorffwys mewn hedd mamgu a tadcu. (souther Welsh)
Heddwch is peace in welsh
The Welsh word for "peace" is pronounced "heddwch." It is phonetically pronounced as "heth-oo-ch."
welsh = tŷ o heddwch
Heddwch i chi.
Rest in peace
peace and happines
Thlalani Gahle
samadhanathil vishramikuvin = Rest in Peace