Reference for Eruvin 145:5

תנו רבנן מי שיש לו חמש נשים מקבלות פרס מבעליהן וחמשה עבדים מקבלין פרס מרביהן רבי יהודה בן בתירה מתיר בנשים ואוסר בעבדים

in the case of the wives<span class="x" onmousemove="('comment',' Since each one is deemed to be intimately associated with her husband's house.');">¹⁴</span> but forbids it in the case of the slaves,<span class="x" onmousemove="('comment',' Who are not so intimately connected with their master.');">¹⁵</span> while R'Judah B'Baba permits this in the case of slaves but forbids it in the case of the wives. Sai Rab, what is R'Judah B'Baba's reason?

Jastrow