Ibn Umar calling slave girl a commodity?

Assalamu Alaikum, I wanted to know about this narration or athar from **Musanaf ibn Abi Shayba, Volume 4 page 289 Tradition 20240** > حدثنا جرير عن منصور عن مجاهد قال كنت مع بن عمر امشي في السوق فإذا نحن > بناس من النخاسين قد اجتمعوا على جارية يقلبونها فلما راوا بن عمر تنحوا > وقالوا بن عمر قد جاء فدنا منها بن عمر فلمس شيئا من جسدها وقال أين > أصحاب هذه الجارية إنما هي سلعة > > Jarir narrated from Mansur from Mujahid who said: I was walking with > Ibn Umar in the market when we came across some slave traders gathered > around a girl, inspecting her. When they saw Ibn Umar, they stepped > aside and said, "Ibn Umar has come." Ibn Umar approached her and > touched a part of her body, then asked, "Where are the owners of this > girl? She is merely a commodity." My Questions are as follows: - Is this narration authentic? - Why does Ibn Umar say things like "She is merely a commodity"? And nobody even asked him what the slave woman was, he had to state that outwardly for no reason, slaves are supposed to be treated like brothers and sisters and they have dignity as well. If you are inspecting them to buy them, buy them and take them home, no need to pass derogatory comments. It leads me to think either the narration is problematic or Ibn Umar is. Thank you in advance for you kind answer.