How does one use subterfuge regarding a bechor? [Concerning] an animal that was pregnant with her first offspring, one declares, “What is in this one’s womb, if [it is] a male, it is an olah,” [if] she gave birth to a male, it is offered as an olah. And [if he declares,] “If it is a female, it is a shelamim-offering,” if she gave birth to a female, it is offered as a shelamim. [If one declares,] “If [the fetus] is a male, it is an olah, and if [it is] a female, it is a shelamim-offering”: [If] she [then] gave birth to a male and a female, the male is offered as an olah, and the female is offered as a shelamim.