Yoreh Deah Siman 267 Seif 25

 

כה נִקְנֶה בַּחֲלִיפִין . וְכֵן נִקְנֶה בִּמְשִׁיכָה, שֶׁתְּקָפוֹ וּמְשָׁכוֹ אֵלָיו. אֲבָל אִם קְרָאוֹ וְהוּא בָּא אֵלָיו, לֹא קְנָאוֹ אֶלָּא אִם כֵּן הוּא קָטָן.

Seif 25

If one acquires a slave through an exchange. he’s acquired through pulling, or forcibly pulling the slave to himself. However if one called the slave and then he came he is not acquired unless he was a child.