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 جَذَعَةً مِنَ الضَّأْنِ»  

that the Prophet ﷺ had given him sheep to distribute among his companions and a male kid was left (after the distribution). When he informed the Prophet ﷺ of it, he said (to him), "Offer it as a sacrifice on your behalf." (Using translation from Bukhārī 2300)  

أَنَّ رَسُولَ اللهِ ﷺ أَعْطَاهُ غَنَمًا يَقْسِمُهَا عَلَى أَصْحَابِهِ فَبَقِيَ عَتُودٌ فَذَكَرَهُ لِرَسُولِ اللهِ ﷺ فَقَالَ «ضَحِّ بِهِ أَنْتَ»