Reference for Zevachim 124:5
אימא ירך בצפון ופניו בצפון אמר רבא רמי גברא אאפיה א"ל אביי אדרבה תריץ ואותיב גברא
Whence do we know it?<span class="x" onmousemove="('comment',' That it had to be on the south side.');"><sup>11</sup></span> - Said R'Huna: Scripture saith, And he shall kill it on the side of the altar northward;<span class="x" onmousemove="('comment',' Ibid. 11.');"><sup>12</sup></span> [this intimates] that the side must be in the north and the front in the south.<span class="x" onmousemove="('comment',' Yerek, translated 'side' literally means 'thigh', hence the legs. Thus the altar must be like a man lying with his legs stretched northward and his face in the south. The side of the altar having this ascent would naturally be the front.');"><sup>13</sup></span>