Pakiṇṇaka 8

The Buddha was staying at Sāvatthī. At that time, the World-honored One had laid down the precept that it’s not allowed to keep prostitutes. Then bhikkhunīs kept personal female attendants who engaged in sex outside to make a living. Laypeople blamed them: “These aren’t renunciates, they’re just prostitutes.” The bhikkhunīs for this reason went and informed the World-honored One. … They answered: “We really did this.” The Buddha said: “From now on, it’s no longer allowed to keep personal attendants, or to make servant women prostitute themselves to make a living. If (a bhikkhunī) keeps one, she breaks a minor vinaya rule.” This is called the rule on female attendants.