Ila [the sage in Yavneh permitted him to take payment for inspecting firstborns (for he was pious, as Rashi states) in the Mishnah of Bekhorot, Chapter 4, Mishnah 5 (29a) and Chapter 6, Mishnah 8, and the sages agreed with him]:
Seder_HaDorot,_Tanaim_and_Amoraim.415:1