It is narrated from Sayyidah Maymunah (may Allah be pleased with her) that when she freed her maidservant, the Prophet (peace and blessings be upon him) said to her: "Had you spared your family from herding the sheep by means of her, that would have been better."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20439