Exchange of One Kind of Food Items for another Kind

4. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from ‘Uthman ibn ‘Isa from Sama‘ah who has said the following: “I once asked him (the Imam) عليه السلام, about wheat and barley. He (the Imam) said, ‘If they are of equal measures it is not harmful.’ He (the narrator) has said, ‘I asked him (the Imam) about flour and wheat. He (the Imam) said, ‘If they are of equal measures it is not harmful.’”