Mishkat al-Masabih 17 Prescribed Punishments كتاب الحدود 31

وَعَنْهُ أَنَّهُ قَالَ: «مَنْ أَتَى بَهِيمَةً فَلَا حَدَّ عَلَيْهِ» . رَوَاهُ التِّرْمِذِيُّ وَأَبُو دَاوُدَ وَقَالَ التِّرْمِذِيُّ: عَنْ سُفْيَانَ الثَّوْرِيِّ أَنَّهُ قَالَ: وَهَذَا أَصَحُّ مِنَ الْحَدِيثِ الْأَوَّلِ وَهُوَ: «مَنْ أَتَى بَهِيمَةً فَاقْتُلُوهُ» وَالْعَمَلُ عَلَى هَذَا عِنْدَ أَهْلِ الْعلم

He reported him as saying, “There is no prescribed punishment for one who has intercourse with an animal.” Tirmidhi and Abu Dawud transmitted it. Tirmidhi quoted Sufyan ath-Thauri as saying that this is sounder than the first tradition, “Kill him who has intercourse with an animal,” (Cf. p. 763) and that the learned act according to this one.