Albert Barnes Commentary Psalms 109:19

"Let it be unto him as the raiment wherewith he covereth himself, And for the girdle wherewith he is girded continually." — Psalms 109:19 (ASV)

Let it be to him as the garment which covers him - He has chosen to put it on, to wear it, to appear in it; so let him constantly feel its consequences. As he is always obliged to wear clothing, so let this be as constantly with him and upon him as his mantle and his sash.

And for a girdle with which he is continually girded - The belt or girdle which he constantly wears. See the notes at (Matthew 5:38).