Musnad Ahmad 27:1411

Muhammad ibn Idris al-Shafi‘i narrated to us, Malik informed us, from Nafi‘, from Ibn ‘Umar, that the Messenger of Allah (ﷺ) said: "Let none of you outbid another upon his sale." He forbade *al-najash* (deceptive bidding), he forbade the sale of *habal al-habala* (the offspring of the offspring), and he forbade *al-muzabana*. *Al-muzabana* is the selling of fresh dates for dried dates by measure, and the selling of grapes for raisins by measure. [‘Abdullah said]: Mus‘ab narrated to us, Malik narrated to us, from Nafi‘, from Ibn ‘Umar, that the Prophet (ﷺ) "forbade *al-najash*," similar to it.