תהילים קיט:קמו פירוש: רש״י

and I shall keep (The acronym of, עֵדְוֹתֶיךָ is דמה בן פֶרֶץ ; the “vav” is vowelized with a “holam,” but in the other instances, it is עֵדֹתֶיךָ ; the “daleth” is vowelized with a “holam.”)