Reference for Bava Batra 314:1
אלא הא מני ר' מאיר היא דאמר אדם מקנה דבר שלא בא לעולם
— But [the fact is that] this [Mishnah] represents the view of<span class="x" onmousemove="('comment',' Lit., 'this according to whom? It is'. ');"><sup>1</sup></span> R. Meir who holds [that] a person may transfer possession of something that is not [yet] in existence.<span class="x" onmousemove="('comment',' While Samuel's enquiry had reference to (v. supra 157a) the view of the Rabbis. ');"><sup>2</sup></span> R. Jacob of Nehar Pekod<span class="x" onmousemove="('comment',' [A town east of Nehardea, v. Obermeyer, op. cit., 270ff.] ');"><sup>3</sup></span> said in the name of Rabina, Come and hear: Ante-dated bonds of indebtedness are invalid<span class="x" onmousemove="('comment',' Since the creditor might unjustly seize the lands which the borrower sold between the date entered in the bond and the actual date of the loan. Only those sold after the actual date are legally mortgaged to the creditor. ');"><sup>4</sup></span>