When a physician consulted the Prophet ﷺ about putting frogs in medicine, he forbade him to kill them. (Using translation from Abū Dāʾūd 3871)   

سَأَلَ طَبِيبُ النَّبِيِّ ﷺ عَنْ ضِفْدَعٍ يَجْعَلُهَا فِي دَوَاءٍ فَنَهَاهُ النَّبِيُّ ﷺ عَنْ قَتْلِهَا