Reference for Bava Metzia 22:4
כי אתא לסורא אמר להו הכי אמר עולא והכי אותביתיה אמר ליה ההוא מרבנן רבן גמליאל מטלטלי אגב מקרקעי הקנה להם רבי זירא קבלה רבי אבא לא קבלה
When he [R. Abba] came to Sura<span class="x" onmousemove="('comment',' Cf. supra 6b. ');"><sup>7</sup></span> he related to those [at the College]: This is what 'Ulla said, and this is the objection that I placed before him. One of the Rabbis then answered him: Rabban Gamaliel made them acquire the movable property through the immovable property.<span class="x" onmousemove="('comment',' The leasing of the ground on which the tithes were lying enabled Joshua and Akiba to acquire the tithes, not because the ground acted for them as their 'hand' or 'agent', but because of the principle that 'movable property, which cannot be pledged as security to a lender, may be acquired together with immovable property, which can be pledged as security to a lender,' by means of the payment of the purchase price of the immovable property (v. Kid 26a). Rabban Gamaliel could therefore have leased to Joshua and Akiba any other piece of ground, with the same effect so far as the acquisition of the tithes is concerned. Even movable property which is received as a gift can be acquired in the same way. (Cf. loc. cit.) ');"><sup>8</sup></span>