The Messenger of Allah ﷺ as saying: Sacrifice only a full-grown animal unless it is difficult for you, in which case sacrifice a lamb. (Using translation from Abū Dāʾūd 2797)   

قَالَ رَسُولُ اللهِ ﷺ لَا تَذْبَحُوا إِلَّا مُسِنَّةً إِلَّا أَنْ يَعْسُرَ عَلَيْكُمْ فَتَذْبَحُوا الْجَذَعَةَ مِنَ الضَّأْنِ  

[Machine] Abdullah bin Umar used to say about the slaughtered animals and bodies that are intact: "And anything above them."  

أَنَّ عَبْدَ اللهِ بْنَ عُمَرَ كَانَ يَقُولُ فِي الضَّحَايَا وَالْبُدْنِ الثَّنِيُّ فَمَا فَوْقَهُ