The Book of Pilgrimage
وَحَدَّثَنِي مُحَمَّدُ بْنُ حَاتِمٍ، حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، عَنِ ابْنِ جُرَيْجٍ، أَخْبَرَنِي أَبُو الزُّبَيْرِ، قَالَ سَمِعْتُ جَابِرَ بْنَ عَبْدِ اللَّهِ، سُئِلَ عَنْ رُكُوبِ الْهَدْىِ، فَقَالَ سَمِعْتُ النَّبِيَّ صلى الله عليه وسلم يَقُولُ " ارْكَبْهَا بِالْمَعْرُوفِ إِذَا أُلْجِئْتَ إِلَيْهَا حَتَّى تَجِدَ ظَهْرًا " .Jabir b. 'Abdullah (Allah be pleased with them) reported that he was asked about riding on a sacrificial animal, and he said:I heard Allah's Messenger (ﷺ) as saying: Ride on it gently, when you have need for it, until you find (another) mount
From Sahih Muslim, whose reports the scholars accept as authentic.