Reference for Niddah 44:63
נפקא מינה דהיכא דאיכא מופנה מצד אחד ומופנה משני צדדין שבקינן מופנה מצד אחד
but it is not available for the purpose in that of sea-monsters.<span class="x" onmousemove="('comment',' Since Scripture contains no other similar expression about them. ');"><sup>53</sup></span> But why is it<span class="x" onmousemove="('comment',' The expression of 'forming'. ');"><sup>54</sup></span> regarded available for deduction in the case of beast? If it be suggested because it is written, And God made the beast of the earth<span class="x" onmousemove="('comment',' Gen. I, 25; an expression of 'making'. ');"><sup>55</sup></span> and it is also written, And out of the ground the Lord God formed every beast of the field,<span class="x" onmousemove="('comment',' Ibid. II, 19; expression of 'forming'. ');"><sup>56</sup></span> is not a similar expression [it may be retorted] also available for deduction in the case of a sea-monster, since it is written, And God made … and every thing that creepeth upon the ground,<span class="x" onmousemove="('comment',' Ibid. I, 25, an expression of 'making' which presumably includes the sea-monsters. ');"><sup>57</sup></span> and it is also written, And God created the great seamonsters?<span class="x" onmousemove="('comment',' Gen. I, 21, an expression of 'creating' which is superfluous in view of that of 'making' (cf. prev. n.) and, therefore, available for deduction. ');"><sup>58</sup></span> — 'Every thing that creepeth' that was written in the previously mentioned verse refers to those on the dry land. What, however, is the practical difference between an expression that is available for deduction on one side and one that is available for deduction on two sides?<span class="x" onmousemove="('comment',' I.e., why is deduction in the latter case preferable to the former? ');"><sup>59</sup></span> — The practical difference is the statement Rab Judah made in the name of Samuel who had it from R. Ishmael:<span class="x" onmousemove="('comment',' The last six words apparently require emendation. ');"><sup>60</sup></span> From any <i>gezerah shawah</i><span class="x" onmousemove="('comment',' V. Glos. ');"><sup>61</sup></span> neither of whose terms is available for deduction<span class="x" onmousemove="('comment',' Lit., 'that is not vacant at all'. ');"><sup>62</sup></span> no deduction may be made;<span class="x" onmousemove="('comment',' Even where no refutation can be offered. ');"><sup>63</sup></span> if one of the terms is available for the purpose, then according to R. Ishmael, a deduction may be made and no refutation may be offered, while according to the Rabbis deduction may be made<span class="x" onmousemove="('comment',' If no refutation can be offered against it. ');"><sup>64</sup></span> but a refutation<span class="x" onmousemove="('comment',' If one can be suggested. ');"><sup>65</sup></span> may be offered; and if both terms are available for deduction, all<span class="x" onmousemove="('comment',' Even the Rabbis. ');"><sup>66</sup></span> agree that deduction may be made and no refutation may be offered. As to R. Ishmael, however, what is the practical difference between a <i>gezerah shawah</i> one of whose terms only is available for deduction and one both of whose terms are available for the purpose? — The practical difference is that where there is one of which one term only is available for deduction and another both of which both terms are available for deduction we must leave the former