Sahih al-Bukhari 6907, 6908
Narrated Hisham's father:
'Umar asked the people, "Who heard the Prophet (ﷺ) giving his verdict 
     regarding abortions?" Al-Mughira said, "I heard him judging that a 
     male or female slave should be given (as a Diya)." 'Umar said, 
     "Present a witness to testify your statement." Muhammad bin Maslama 
     said, "I testify that the Prophet (ﷺ) gave such a judgment."
حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُوسَى، عَنْ هِشَامٍ، عَنْ أَبِيهِ، أَنْ عُمَرَ، نَشَدَ النَّاسَ مَنْ سَمِعَ النَّبِيَّ صلى الله عليه وسلم قَضَى فِي السِّقْطِ وَقَالَ الْمُغِيرَةُ أَنَا سَمِعْتُهُ قَضَى فِيهِ بِغُرَّةٍ عَبْدٍ أَوْ أَمَةٍ‏.‏   قَالَ ائْتِ مَنْ يَشْهَدُ مَعَكَ عَلَى هَذَا فَقَالَ مُحَمَّدُ بْنُ مَسْلَمَةَ أَنَا أَشْهَدُ عَلَى النَّبِيِّ صلى الله عليه وسلم بِمِثْلِ هَذَا‏.‏