Reference for Zevachim 49:13
אמר רב חסדא אמר רב ירמיה בר אבא השוחט צריך שיתן
[this means,] of the life blood, but not of the blood of the skin or of the draining blood;<span class="x" onmousemove="('comment',' The life blood is the first blood that gushes out; the draining blood is that which follows.');"><sup>7</sup></span> 'of the blood of the bullock' [implies,] he is to receive the blood [direct] from the bullock.<span class="x" onmousemove="('comment',' And not permit it to pour on to the pavement first; if he does, it is unfit.');"><sup>8</sup></span> For if you think that 'of the blood of the bullock' [is meant literally] as it is written, [viz. ,] of the blood [indicating] even a portion of the bloo [only], Surely Rab said: He who slaughters [the sacrifice] must receive all the blood of the bullock, for it says, And all the remaining blood of the bullock shall he pour out.<span class="x" onmousemove="('comment',' Ibid. 7.');"><sup>9</sup></span> Hence 'from the blood of the bullock' means, he is to receive the blood [direct] from the bullock; for [the author of this exegesis] holds: You subtract, add, and interpret.<span class="x" onmousemove="('comment',' You may subtract a letter from one word and add it to another, where the context warrants it, and then interpret the text in accordance with n osn rpv this alteration. Thus here the partitive ('of' or 'from') is removed from blood, and added to the bullock, so that it reads: and he shall take the (not, of the) blood from the bullock.');"><sup>10</sup></span> The [above] text [stated]: Rab said: He who slaughters [the sacrifice] must receive all the blood of the bullock, for it says, 'And all the remaining blood of the bullock shall he pour out'. But surely this is written of the remainder [of the blood]?<span class="x" onmousemove="('comment',' It refers to the pouring out of the remainder, and not to receiving at all.');"><sup>11</sup></span> - Since it is inapplicable to the remainder, for all the blood is not available [at the time],<span class="x" onmousemove="('comment',' As some of it has already been sprinkled on the horns of the altar.');"><sup>12</sup></span> apply it to receiving. Rab Judah said in Samuel's name: He who slaughters must raise the knife upwards.<span class="x" onmousemove="('comment',' So that none of the blood on the knife runs into the bowl.');"><sup>13</sup></span> for it is said, 'And he shall take of the blood of the bullock,' but not of the blood of the bullock plus something else. And with what does he wipe the knife? - Said Abaye: With the edge of the bowl,<span class="x" onmousemove="('comment',' Taking care that the blood does not flow into it.');"><sup>14</sup></span> as it is written, Wipers [cleaners] of gold.<span class="x" onmousemove="('comment',' Ezra 1, 10; E.V. bowls of gold. Abaye connects the Heb. kefore with kapper, to wipe away (whence its general meaning of to atone or forgive) .');"><sup>15</sup></span> R'Hisda said in the name of R'Jeremiah B'Abba: He who slaughters must let