Bava Metzia 48 - Acquiring by Paying Money

Rabbi Yochanan said that under Biblical law, the payment of money acquires movables. And why did the Rabbis say that drawing an object to oneself acquires the movable property, but paying money does not? Out of concern that the buyer may pay but not take delivery of the goods, then if a fire breaks out, the seller would not take sufficient measures to save them, since he has already been paid.
Resh Lakish said that acquisition by drawing to oneself is explicitly indicated in the Torah, "… if you sell or buy from the hand of your fellow …"
The final law follows Rabbi Yochanan