Mughira bin Shuba reported,
Umar 
consulted the people about a woman who miscarries her child due to assault. I said, "The Messenger of Allah ﷺ ruled in such a case that compensation of a slave, male or female, be paid."Umar said, "Bring me someone who can corroborate your testimony."Then Muhammad bin Maslama testified that he had witnessed the Prophet ﷺ make that very ruling.
Azami 6871
Sahihعن المغيرة بن شعبة رضي الله عنه قال
استشار عمر رضي الله عنه الناس في إملاص المرأة، فقلت: قضى رسول الله ﷺ فيه بغرة عبد أو أمة، فقال: ائتني بمن يشهد معك… فشهد محمد بن مسلمة أنه شهد النبي ﷺ قضى به.
Bukhari narrated it in the Book of Blood Money (6905–6908), from Musa bin Ismail, who said, "Wahib narrated to us, Hisham narrated to us, from his father, from Mughira bin Shuba," in this manner. And also from Ubaydullah bin Musa, from Hisham, from his father, that Umar called upon the people to testify... the hadith. And through the route of Zaida, "Hisham bin Urwa narrated to us, from his father, that he heard Mughira bin Shuba narrate from Umar." This route makes clear that Urwa bin Zubayr heard it directly from Mughira bin Shuba without any intermediary.However, Muslim narrated it in the Book of Qasama (1689) through several routes from Waki, from Hisham bin Urwa, from his father, from Miswar bin Makhrama, who said, "Umar bin Khattab consulted the people about a woman miscarrying, and Mughira said..." the hadith. Miswar bin Makhrama was a minor companion, and Urwa bin Zubayr heard hadiths from him, so it is possible that Urwa had two teachers for this hadith.As for the hadith master Daraqutni, in his book Tatabbu (85), he critiqued Muslim on this point and judged that Waki had erred by contradicting the other students of Hisham, who did not mention "Miswar." He said, "And that is the correct view."