Peace be upon you. Is it permissible to exchange wheat flour for wheat?

Scholars have differed regarding the ruling on selling grain for its flour. Al-Shafi'i and Abu Hanifa held that it is impermissible due to the presence of excess (tafadhul), and this is the closer to the correct view. Whereas Malik permitted it by measure (kaylan), and Ahmad permitted it by weight (waznan), and the Dhahiris permitted it absolutely, whether by measure or by weight.