Ibn Ezra on Leviticus 4:32

ואם כבש. ואם הביא ממין הכבש לחטאת יביא נקבה כמו שעירת עזים: AND IF HE BRING A LAMB. If he brings a sin offering from the lamb species then he shall bring a female, as in the case of the she-goat.⁵⁴When one brings a goat as a sin offering, he brings a she-goat. Similarly, when one chooses to bring a lamb as a sin offering he must bring a female.