Those are the reasons I heard Chesed over Gevurah It was probably not Rachamim because Rachamim is Tiferes which is also on the right side, and to be different from the goyim. buttons are a newer invention. Rebishe shirts only have 3 buttons and slip over the head and don’t have cuffs just long sleeves without cuffs kind of like what a short sleeve shirt has but longer. The rebishe bekishes with the velvet down the middle have hooks (shtrokes) instead of buttons.
Menu