פירוש על עבודה זרה 126:5

The Talmud raises a difficulty on R. Hisda’s resolution. If R. Hisdah was correct then instead of the distinction taught in the baraita itself, between a case where the employer gave them the dinar first and a case where he paid them back after they had bought the food, the distinction should have been drawn with regard to the shop-keeper’s relationship with the employer. If the shop-keeper regularly extends credit to the employer it is forbidden, but if he does not, it is permitted.