Kommentar zu Ijow 2:8

to scratch himself with Heb. להתגרד.This word is spelled with a “dalet.” It is a Mishnaic expression (Rosh Hashanah 27b): “If he scraped it (גרדו) and reduced it to its normal size,” but גורר with a “reish” is only an expression of dragging, like (Shabbath 29b), “A person may drag a bed or a bench.”