Midrasch zu Wajikra 16:14

11) (Vayikra 16:14) ("And he shall take the blood of the bullock, and he shall sprinkle with his finger on the face of the kaporeth (the ark cover) to the east; and before the kaporeth shall he sprinkle seven times of the blood with his finger.") "And he shall take the blood of the bullock": He takes it from the one who was stirring it. "and he shall sprinkle": and not let it drip (from his finger). "and he shall sprinkle": and not fling. "his finger": "his finger" is written here and elsewhere (Vayikra 14:16) in respect to a leper). Just as "his finger" there is the most dexterous, i.e., the index finger of the right hand, so, "his finger" here.

12) "upon the face of the ark cover to the east": This is the archetype (binyan av) for "face" always connoting "east."

13) A variant: "on the face of the ark cover to the east": He did not aim at sprinkling above or below, but made a whip-swing motion.