Hadithcore
Sahih Muslim, 1961 j
sahih

This hadith has been narrated on the authority of Shu'ba with the same chain of transmitters, but did not mention tht doubt (expressed in his statement) That is (the goat of less than a year) is better than a goat of more than one year.

وَحَدَّثَنَاهُ ابْنُ الْمُثَنَّى، حَدَّثَنِي وَهْبُ بْنُ جَرِيرٍ، ح وَحَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، أَخْبَرَنَا أَبُو عَامِرٍ الْعَقَدِيُّ، حَدَّثَنَا شُعْبَةُ، بِهَذَا الإِسْنَادِ ‏.‏ وَلَمْ يَذْكُرِ الشَّكَّ فِي قَوْلِهِ هِيَ خَيْرٌ مِنْ مُسِنَّةٍ ‏.‏

References2 variants
In-Book Reference
Book 35, Hadith 15
USC-MSA web (English) reference
Book 22, Hadith 4832 (deprecated numbering scheme)