Jabir (RAA) narrated that Allah's Messenger (ﷺ) said:

"Sacrifice only a full-grown animal unless it is difficult for you, in which case you should sacrifice a (six to ten month old) sheep." Reported by Muslim.

وَعَنْ جَابِرٍ ‏- رضى الله عنه ‏- قَالَ: قَالَ رَسُولُ اَللَّهِ ‏- صلى الله عليه وسلم ‏-{

لَا تَذْبَحُوا إِلَّا مُسِنَّةً, إِلَّا أَنْ يَعْسُرَ عَلَيْكُمْ فَتَذْبَحُوا جَذَعَةً مِنَ اَلضَّأْنِ

} رَوَاهُ مُسْلِم ٌ (1772)‏ .‏