Sources : Leontophone
Gaius Julius Solinus [3rd century CE] (De mirabilibus mundi / Polyhistor, Chapter 27.21-22): [Chapter 27.21] I have heard of little creatures called leontophoni, which are caught and incinerated. Flesh polluted with a dusting of their ashes, and planted at crossroads may kill lions, if they take never so small a piece thereof. [Chapter 27.22] Therefore, lions oppress the leotophoni with a natural hatred. When given opportunity, they kill them; they abstain from biting them, but tear them to pieces with the strength of their paws. - [Arwen Apps translation, 2011]
Isidore of Seville [7th century CE] (Etymologies, Book 12, 2:34): The leontophonos is a small animal; it is so named because when captured it is burnt, and its flesh, sprinkled with ash and placed at the crossroads, kills lions, if they take even a small amount of it. - [Barney, Lewis, et. al. translation]
Aberdeen Bestiary [circa 1200 CE] (folio 8r):We learn of small beasts called leontophones, lion-killers. When captured, they are burnt; meat contaminated by a sprinkling of their ashes and thrown down at crossroads kills lions, even if they eat only a small an amount. For this reason, lions pursue leontophones with an instinctive hatred and, when they have the opportunity, they refrain from biting them but kill them by rending them to pieces under their paws.
Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Quadrupeds 4.63): A leoncophana, as Solinus and Jacobus say, is a small beast, which, when caught, is burnt, that its ashes may be sprinkled on the track of the lions. For the lions are killed if they touch even a little of them. Therefore the lions, with their natural hatred, pursue the beast, and break it when it is caught. But the lions die immediately if they bite the beast. It is true that it sprinkles urine against the approaching lion, knowing that this is also fatal to the lion. - [Badke translation/paraphrase]