19. A number of our people have narrated from Sahl ibn Ziyad and Ahmad ibn Muhammad from all from ibn abu Nasr who has said the following: “Once a man asked al-Rida’ عليه السلام, about a pair of pigeons which hatched chicks with him; if a bird can mate a mother bird or daughter bird. He (the Imam) said, ‘It is not harmful with what is in animals.’”