What did Ibn Abza and Ibn Abi Aufa say about the practice of As-Salam in the lifetime of the Prophet Muhammad (saw)?
 Narrated Shu`ba:                     Muhammad or `Abdullah bin Abu Al-Mujalid said, "Abdullah bin Shaddad and Abu Burda differed regarding As-Salam, so they sent me to Ibn Abi `Aufa and I asked him about it. He replied, 'In the lifetime of Allah's Apostle, Abu Bakr and `Umar, we used to pay in advance the prices of wheat, barley, dried grapes and dates to be delivered later. I also asked Ibn Abza and he, too, replied as above.' "