Bava Metzia 111A

וזה, לפי שאין פעולתו אצלו. היכי דמי? אי דאמר להו שכרכם עלי ⁠– שכרו עליו הוא, דתניא: השוכר את הפועל לעשות בשלו והראהו בשל חבירו ⁠– נותן לו שכרו משלם, וחוזר ונוטל מבעל הבית מה שההנה אותו!

And that one, the middleman, is exempt because his work is not performed for him. The Talmud asks: What are the circumstances of this case? If the middleman said to them: Your wages are incumbent upon me, his wages are indeed upon him, as the one who hired the workers bears full responsibility. As it is taught in a baraita: With regard to one who hires a laborer to perform work in his own field, and the employer inadvertently showed the laborer a field belonging to another in which he should work, the employer must give the laborer his full wages; and in addition, the employer goes back and takes from the owner of the field in which he worked the value of the benefit that owner received from the laborer. The employer is entitled to claim from the owner of the field the profit that owner gained from the work, but not the entire wages of the laborer. This indicates that one who says: Your wage is incumbent upon me, is responsible for the arrangement.

לא צריכא, דאמר להו: שכרכם על בעל הבית.

The Talmud explains: No, it is necessary to state this halakha where the middleman said to them: The obligation to pay your wages is incumbent upon the employer, in which case they share responsibility for the payment and neither violates the prohibition.

יהודה בר מרימר אמר ליה לשמעיה: זיל אגור לי פועלים, ואימא להו: שכרכם על בעל הבית, מרימר ומר זוטרא אגרי להדדי.

The Talmud relates: Yehuda bar Mareimar would say to his attendant: Go hire workers for me and say to them: Your wages are upon the employer. Yehuda bar Mareimar instructed the attendant to do this in order to avoid violating the prohibition of delaying payment of wages. Mareimar and Mar Zutra would hire workers for each other for the same reason.