I heard my father narrating from a man who said, "We were with the Prophet ﷺ two days before the day of sacrifice, exchanging two yearling sheep for one two-year-old, when the Messenger of Allah ﷺ said, 'A yearling suffices for what a two-year-old suffices.'"
أخبرنا محمد بن عبد الأعلى قال حدثنا خالد قال حدثنا شعبة
سمعت أبي يحدث عن رجل قال كنا مع النبي ﷺ قبل الأضحى بيومين نعطي الجذعتين بالثنية فقال رسول الله ﷺ إن الجذعة تجزئ ما تجزئ منه الثنية
No references are available.
[Its isnad is sahih] Ahmad reported it: 5/368, from the hadith of Shubah, through this route. See the previous hadith. It is also in Al-Kubra, hadith no. 4474.